Derogatory (5)
I believe the answer is:
snide
'derogatory' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for snide that I've seen before include "Sneering, supercilious" , "Sneering in a sly way - dines out on it" , "Derogatory, sneering" , "Maliciously mocking" , "Supercilious, malicious" .)