Sly and nasty (5)
I believe the answer is:
snide
'sly and nasty' 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 "Maliciously mocking" , "such remarks aren't nice" , "Sneering, supercilious" , "Derogatory, mocking" , "Dines (anag.)" .)