Ken's going off yellow style (4)
I believe the answer is:
chic
'style' is the definition.
(chic can mean elegance or style)
'ken's going off yellow' is the wordplay.
'going off' is a deletion indicator.
'yellow' becomes 'chickens' (I've seen this before).
'chickens' with 'kens' taken away is 'CHIC'.
(Other definitions for chic that I've seen before include "Snazzy" , "Elegant and stylishly fashionable" , "cool" , "Modish" , "Elegantly fashionable" .)