Boss meets key member where horses are bred (4,4)
I believe the answer is:
stud farm
'where horses are bred' is the definition.
(place for breeding horses)
'boss meets key member' is the wordplay.
'boss' becomes 'stud' (both can mean a metal decoration).
'meets' means one lot of letters go next to another.
'key' becomes 'f' (musical key).
'member' becomes 'arm' (member can mean a limb).
'stud'+'f'+'arm'='STUD-FARM'
(Other definitions for stud farm that I've seen before include "Horse-breeding establishment" , "place of breeding" , "Horses are bred and raised here" , "Horse-breeding place" , "place to breed" .)