Criminal chasing fellow gangster gets bird (6)
I believe the answer is:
falcon
'bird' is the definition.
(falcon is a kind of bird)
'criminal chasing fellow gangster' is the wordplay.
'criminal' becomes 'con' (abbreviation for 'convict').
'chasing' is a charade indicator (letters next to each other).
'fellow' becomes 'f' (abbreviation - of a society etc.).
'gangster' becomes 'al' (Al Capone).
'f'+'al'='fal'
'con' put after 'fal' is 'FALCON'.
'gets' is the link.
(Other definitions for falcon that I've seen before include "Clan of (anag) - raptor" , "that's seen flying" , "Hunter winged" , "Hunting bird, may be peregrine" , "A hunting bird, may be peregine" .)