Boxer formerly with concern to find target (4,6)
I believe the answer is:
clay pigeon
'target' is the definition.
(clay pigeon is a kind of target)
'boxer formerly with concern' is the wordplay.
'boxer formerly' becomes 'clay' (Muhammad Ali was born Cassius Clay).
'with' means one lot of letters go next to another.
'concern' becomes 'pigeon' (as in the phrase 'not my pigeon').
'clay'+'pigeon'='CLAY PIGEON'
'to find' is the link.
(Other definitions for clay pigeon that I've seen before include "Trap shooting target" , "Disc fired into the air as target for shooting" , "hard bird to shoot?" , "Trap shooter's target" , "target of gunmen" .)