Snappy answer (6)
I believe the answer is:
retort
'snappy answer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for retort that I've seen before include "Lab equipment" , "Sharp response; lab item" , "Lab. vessel; quip" , "Part of chemist's equipment" , "Answer in retaliation" .)