The most common and most likely answer to this crossword clue is the 9 letter word STICKLERS
I've seen this crossword clue in The Daily Telegraph
S
T
I
C
K
L
E
R
S
Buddy explains!
The straight part
We know that "Martinets" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case martinets = sticklers.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does STICKLERS mean?
STICKLERS noun- A referee or adjudicator at a fight, wrestling match, duel, etc. who ensures fair play.
- Someone who insistently advocates for something.