Bird or jailbird pocketing a penny (5)
I believe the answer is:
capon
'bird' is the definition.
(capon is a kind of bird)
'jailbird pocketing a penny' is the wordplay.
'jailbird' becomes 'con' (I've seen this in other clues).
'pocketing' is an insertion indicator.
'penny' becomes 'p' (short for pence).
'a'+'p'='ap'
'con' enclosing 'ap' is 'CAPON'.
'or' acts as a link.
(Other definitions for capon that I've seen before include "Male fowl fattened for eating" , "Castrated male chicken" , "A tasty bird" , "Castrated fowl, for eating" , "Bird fattened for eating" .)