Self-righteous
I believe the answer is:
smug
'self-righteous' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for smug that I've seen before include "Self-satisfied, complacent" , "Unpleasantly complacent" , "Arrogantly complacent" , "Smirking" , "goody-goody" .)