The perimeter of the grid spells out a phrase (7 words, 28 letters) that is a quotation from a worker to a ruler. The name of the person the quote is attributed to should be written in the grey box at the foot of the grid as well as solving all the clues and filling in the missing letters in the perimeter (5 in total, which are coincidentally exactly the consonants of the last word of the phrase)
Across:
7. Yankee and his chopper is ordinate, say? (1-4)
8. Poo zone holds back animal exhibitors (3)
9. Lots of paper in student-free domains (5)
10. Put short lad on inactive, druglike substance (7)
12. Reseat unsettled diners (6)
14. Plants with cone-shaped flowerheads for dinner (6)
15. Two balls and hard… pleased expression! (3)
16. Eddy starts to sample water in Russian lake (5)
Down:
1. English own lacking victory Scots possess (3)
2. Dignify worship (5)
3. Chink found in grim armour (4)
4. Sierra represents three fifths of county (3)
5. Zeta-IV is breaking news in Russia (8)
6. Melancholy Republican's old hat (8)
10. Actor Al, not popular, has llama (4)
11. Horde of American Indians after diamonds? Just the opposite! (5)
13. Once upon a time in the middle of a masterstroke… (4)
14. …quiet house serves soup (3)