Peacockish (4)
I believe the answer is:
vain
'peacockish' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for vain that I've seen before include "is full of himself" , "Conceited, arrogant" , "Conceited and ineffectual" , "Having too much pride in one's appearance" , "Conceited - or a waste of time" .)