Elegant young fowl losing kilo (4)
I believe the answer is:
chic
'elegant' is the definition.
(I've seen this before)
'young fowl losing kilo' is the wordplay.
'young fowl' becomes 'chick' (young bird).
'losing' indicates named letters should be taken away.
'kilo' becomes 'k' (phonetic alphabet: alpha, bravo, charlie etc.).
'chick' with 'k' taken away is 'CHIC'.
(Other definitions for chic that I've seen before include "Trendy" , "A la mode" , "Well turned out" , "Modish" , "French elegance" .)