Chicken backing away from gangster (5)
I believe the answer is:
capon
'chicken' is the definition.
(capon is a kind of chicken)
'backing away from gangster' is the wordplay.
'backing away from' means to remove the last letter (the back letter is removed).
'gangster' becomes 'capone' (Al Capone).
'capone' with its last letter taken off is 'CAPON'.
(Other definitions for capon that I've seen before include "one fattened specially" , "A tasty bird" , "Emasculated fowl" , "Castrated rooster fattened for eating" , "Castrated fowl, for eating" .)