Young bird without tail is fashionable (4)
I believe the answer is:
chic
'fashionable' is the definition.
(chic means stylish or fashionable)
'young bird without tail' is the wordplay.
'young bird' becomes 'chick' (I've seen this before).
'without tail' means to remove the last letter.
'chick' with its final letter taken away is 'CHIC'.
'is' is the link.
(Other definitions for chic that I've seen before include "Smart and stylish, in a French kind of way" , "Fashionably elegant" , "Snazzy" , "Fashionably smart" , "Well turned out" .)