The most common and most likely answer to this crossword clue is the 9 letter word TRENCHANT
I've seen this crossword clue in The Guardian
T
R
E
N
C
H
A
N
T
More clues leading to the result TRENCHANT
- Keen worker at bottom of ditch
- Biting fish swallowing angler’s last insect
- Try short rivet that's penetrating
- Keen soldier in WW1 battlefield?
- Cutting song after resistance during number
- Effective Somme soldier?
- Cutting ditch with worker
- Powerful transport turning right to start with
- Forthright six-footer by ditch
- Distinctly defined charm associated with Turkey
Buddy explains!

The straight part
We know that "Cutting" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cutting = trenchant.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 TRENCHANT mean?
TRENCHANT adjective- Fitted to trench or cut; gutting; sharp.
- Keen; biting; vigorously articulate and effective; severe.