The hardest crossword you'll do today!

Question

This could well be the most difficult crossword you do today!

Please note that the use of Google and other search engines is STRICTLY FORBIDDEN.

(Of course, I have no way of policing this, but if you do decide to cheat and comb the Internet for the answers then the letters in the shaded squares can be rearranged to describe what I think of you!)

Good luck!

Across:
1. Object resembled by the trichiuriform fish Trichiurus lepturus. (4)
5. Given name of US director Hooper, who directed the 1995 adaptation of the Stephen King short story, The Mangler. (4)
7. German royal house producing 4 British monarchs who shared their name with the thoroughfare on which South Woodford’s tube station is situated. (7)
8. Family of flowering plants including spinach (Spinacia oleracea) and beet (Beta vulgaris). (13)
10. Alternative name of the evergreen tree, Pouteria campechenia, whose fruit is commonly known as an ‘egg fruit’. (8)
11. Battle of 14 March 1590, during the French Wars of Religion, fought on the plains of Épieds in Eure, France. (4)
12. Department of northern France, home to the commune of Épieds, site of the 16th century Battle of Ivry. (4)
13. Common name of the fruit of the canistel (Pouteria campechenia), an evergreen tree native to Latin America. (3,5)
15. London tube station formerly known as 'George Lane' after the street on which it stands. (5,8)
18. Stephen King short story, The _______, adapted for the big screen by Tobe Hooper in 1995. (7)
19. “____’s fingers” – a colloquial name of the okra plant (Abelmoschus esculentus). (4)
20. Ancient country, neighbour of Edom and positioned on “The King’s Highway”, the trade route linking Egypt and Mesopotamia. (4)

Down:
2. Kingdom established in the 13th century BC, bordering Moab and drawing much of its livelihood from the caravan trade between north Africa and southwest Asia. (4)
3. Surgical procedure carried out for conditions including cancer, enlarged thyroid gland (“goitre”) and Graves’ disease. (13)
4. Swelling in the neck caused by enlargement of the thyroid gland, sometimes treated surgically with a thyroidectomy. (6)
5. Pertaining to the genus Trichiurus or family Trichiuridae (e.g. the beltfish, Trichiurus lepturus). (13)
6. Genus of the beet, member of the Amaranthaceae family of plants. (4)
9. North African country at the end of “The King’s Highway”, a historic trade route passing through Edom, Moab and other ancient kingdoms. (5)
10. Two-player board game, contested in the four FIDE Grand Prix 2019 tournament events held sequentially in Moscow, Riga, Hamburg and Jerusalem. (5)
14. ______ Lane, road in the London suburb of South Woodford; also the given name of several British monarchs in the Hanover dynasty. (6)
16. Plant of the Abelmoschus genus, alternatively known as “gumbo” or “lady’s fingers”. (4)
17. European city which hosted the second event of the FIDE Grand Prix series of chess tournaments in 2019. (4)

Answer 1

Finished crossword

No googling is required because

Each answer is given away by another clue:

Across:
1. Object resembled by the trichiuriform [5d] fish Trichiurus lepturus. (4)
5. Given name of US director Hooper, who directed the 1995 adaptation of the Stephen King short story, The Mangler [18a]. (4)
7. German royal house producing 4 British monarchs who shared their name with the thoroughfare on which South Woodford’s [15a] tube station is situated. (7)
8. Family of flowering plants including spinach (Spinacia oleracea) and beet (Beta [6d] vulgaris). (13)
10. Alternative name of the evergreen tree, Pouteria campechenia, whose fruit is commonly known as an ‘egg fruit’ [13a]. (8)
11. Battle of 14 March 1590, during the French Wars of Religion, fought on the plains of Épieds in Eure [12a], France. (4)
12. Department of northern France, home to the commune of Épieds, site of the 16th century Battle of Ivry [11a]. (4)
13. Common name of the fruit of the canistel [10a] (Pouteria campechenia), an evergreen tree native to Latin America. (3,5)
15. London tube station formerly known as 'George [14d] Lane' after the street on which it stands. (5,8)
18. Stephen King short story, The _______, adapted for the big screen by Tobe [5a] Hooper in 1995. (7)
19. “____’s fingers” – a colloquial name of the okra [16d] plant (Abelmoschus esculentus). (4)
20. Ancient country, neighbour of Edom and positioned on “The King’s Highway”, the trade route linking Egypt [9d] and Mesopotamia. (4)

Down:
2. Kingdom established in the 13th century BC, bordering Moab [20a] and drawing much of its livelihood from the caravan trade between north Africa and southwest Asia. (4)
3. Surgical procedure carried out for conditions including cancer, enlarged thyroid gland (“goitre”) [4d] and Graves’ disease. (13)
4. Swelling in the neck caused by enlargement of the thyroid gland, sometimes treated surgically with a thyroidectomy [3d]. (6)
5. Pertaining to the genus Trichiurus or family Trichiuridae (e.g. the beltfish [1a], Trichiurus lepturus). (13)
6. Genus of the beet, member of the Amaranthaceae [8a] family of plants. (4)
9. North African country at the end of “The King’s Highway”, a historic trade route passing through Edom, [2d] Moab and other ancient kingdoms. (5)
10. Two-player board game, contested in the four FIDE Grand Prix 2019 tournament events held sequentially in Moscow, Riga, [17d] Hamburg and Jerusalem. (5)
14. ______ Lane, road in the London suburb of South Woodford; also the given name of several British monarchs in the Hanover [7a] dynasty. (6)
16. Plant of the Abelmoschus genus, alternatively known as “gumbo” or “lady’s [19a] fingers”. (4)
17. European city which hosted the second event of the FIDE Grand Prix series of chess [10d] tournaments in 2019. (4)

The final message is

APRIL FOOL, formed by anagramming letters in the shaded squares.