Fight and fight for bird (7)
I believe the answer is:
sparrow
'bird' is the definition.
(sparrow is a kind of bird)
'fight and fight' is the wordplay.
'fight' becomes 'spar' (sparring is a kind of fighting).
'and' is a charade indicator (letters next to each other).
'fight' becomes 'row'.
'spar'+'row'='SPARROW'
'for' is the link.
(Other definitions for sparrow that I've seen before include "one on the wing" , "Common town bird" , "Singing bird" , "a British resident" , "Bird with cockney associations" .)