Self-congratulatory (4)
I believe the answer is:
smug
'self-congratulatory' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for smug that I've seen before include "looking pleased with itself" , "goody-goody" , "Be envious of" , "Smooth" , "Self-satisfied, complacent" .)