Stinging remark (4)
I believe the answer is:
barb
'stinging remark' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for barb that I've seen before include "Arrowhead projection" , "Sharp spike pointing backward" , "Aggressive remark intended to have a telling effect" , "Slight" , "Small prong on larger point" .)