Cryptic crossword: a little je ne sais quoi

Question

Ten clues have word-play and definition that appear not to match. The result of the word-play must be entered into the grid. To assist solvers one extra letter appears in the word-play of all other answers (this letter is not entered into the grid). Taken in clue order, these extra letters spell out most of a phrase describing what hidden step must be taken for the other ten clues to work. The 6-letter word missing from this phrase must be given to complete the puzzle.

Across

1.  Regular woman with 'abbreviated' lord... (6)
4. ...wants sailor to replace sulphur (first) in concentrated extracts (8)
10. Remedy fleas dancing about vixen's head (5)
11. 7 embers make dark-grey drawing materials (9)
12. Arrange 'no coital' rental (8)
13. Mashed turnips excite... (4,2)
14. ...Auntie Alice holding British beverage (3)
15. Agree to back Queen against new church competition (11)
18. Containing N disorganised touring notes (11)
19. His vanguard of soldiers, officers, NCOs... (3)
20. ...accomplish reassembly of Titania (6)
22. Sensitive saint corrected Eblis, taking measure (8)
26. Intend to settle two thousand between one and one gold-concealing framed entrance (9)
27. Trainee doctor disinclined to move (5)
28. Police singer consuming for example drug before trying (8)
29. Govern Dorchester's interior for seller (6)

Down

1. Raise interjection, expressing grief, over article pertaining to the nose (5)
2. Unwilling bombast about dodgy clue and collection of good books (9)
3. Turn aside vaster frolics (5)
5. Arm British leaders of African soldiers (4)
6. Leaderless police force allow, after 100 important dates, additional people or things (9)
7. Seat flesh (5)
8. That man gives money for existing back first then leads to Atlas's narrative: endless, laborious, futile (9)
9. Hunt around for redesigned strong cue (8)
14. Try wigwam perhaps before native loses head (9)
15. Mix gel in coyly in an overly sweet way (9)
16. Aroused about rejection, act takes note -- is shuttered (8)
17. Leak vital fluid after crushing stone causes red-faced discomfort (9)
21. Time part-time staff (5)
23. Evens for issue in the continuation (5)
24. Solid condensation of alcohol and acid (5)
25. Spain's unwrapped bread (4)

Answer 1

Grid:

Clue solutions etc.:

D 1a. NORMAL NORMA + LD Regular woman with 'abbreviated' lord... (6)
E 4a. ABSENCES AB replaces first S in ESSENCES ...wants sailor to replace sulphur (first) in concentrated extracts (8)
F 10a. SALVE FLEAS* about V Remedy fleas dancing about vixen's head (5)
I 11a. CHARCOALS CHAIR + COALS 7 embers make dark-grey drawing materials (9)
* 12a. LOCATION Arrange 'no coital' rental (8)
N 13a. STIR UP TURNIPS* Mashed turnips excite... (4,2)
I 14a. TEA substring ...Auntie Alice holding British beverage (3)
* 15a. CONCURRENCE CONCUR ER< N CE Agree to back Queen against new church competition (11)
T 18a. NITROGENOUS (TOURING NOTES)* Containing N disorganised touring notes (11)
* 19a. SON first letters His vanguard of soldiers, officers, NCOs... (3)
I 20a. ATTAIN TITANIA* ...accomplish reassembly of Titania (6)
* 22a. SENSIBLE ST EBLIS* with EN inserted Sensitive saint corrected Eblis, taking measure (8)
O 26a. IMMIGRATE MM between I and I G(OR)ATE Intend to settle two thousand between one and one gold-concealing framed entrance (9)
E 27a. INERT TRAINEE* Trainee doctor disinclined to move (5)
T 28a. ESSAYING STING consuming SAY, E before Police singer consuming for example drug before trying (8)
R 29a. VENDOR substring Govern Dorchester's interior for seller (6)
A 1d. NASAL (ALAS + AN)* Raise interjection, expressing grief, over article pertaining to the nose (5)
N 2d. RELUCTANT RANT about (CLUE* NT) Unwilling bombast about dodgy clue and collection of good books (9)
S 3d. AVERT VASTER* Turn aside vaster frolics (5)
* 5d. BRAS BR + A(-frican) S(-oldiers) Arm British leaders of African soldiers (4)
L 6d. ETCETERAS (-m)ET (LET after C) ERAS Leaderless police force allow, after 100 important dates, additional people or things (9)
* 7d. CHAIR ddef Seat flesh (5)
A 8d. SISYPHEAN HE, (PAYS IS)< first, then A(-tlas's) N(-arrative) That man gives money for existing back first then leads to Atlas's narrative: endless, laborious, futile (9)
T 9d. SCROUNGE (STRONG CUE)* Hunt around for redesigned strong cue (8)
* 14d. TENTATIVE TENT + (-n)ATIVE Try wigwam perhaps before native loses head (9)
E 15d. CLOYINGLY (GEL IN COYLY)* Mix gel in coyly in an overly sweet way (9)
D 16d. UNOPENED (UP about NO) + (DEED takes N) Aroused about rejection, act takes note -- is shuttered (8)
T 17d. NOSEBLEED BLEED after STONE* Leak vital fluid after crushing stone causes red-faced discomfort (9)
* 21d. TEMPS ddef Time part-time staff (5)
* 23d. SUITE even-numbered letters of ISSUEINTHE Evens for issue in the continuation (5)
O 24d. ESTER but I don't understand the wp yet; something to do with STEREO? Solid condensation of alcohol and acid (5)
* 25d. PAIN (-s)PAIN(-s) Spain's unwrapped bread (4)

Missing six-letter word is

FRENCH.

What's going on:

The ten clues where wordplay and definition appear to mismatch are for words in French, not English. E.g., "chair" means a thing you sit on in English but means "flesh" in French. The surplus letters say DEFINITIOE TRANSLATED TO; I think the E in 27a was meant to be an N; it happens that replacing TRAINEE with the nearly-synonymous INTERN would fix the problem, except that "intern doctor" feels a bit strange so maybe make it "Sick intern ...". So the completed phrase is DEFINITION TRANSLATED TO FRENCH.