Nasty, as a remark (5)
I believe the answer is:
snide
'nasty as a remark' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for snide that I've seen before include "Slyly derogatory" , "Indirectly mocking" , "Mean, base" , "Derogatory, mocking" , "Sneering, supercilious" .)