Headgear given to Oscar for playing bridge? (4)
I believe the answer is:
capo
'for playing bridge?' is the definition.
(device put on a guitar - bridge is a guitar part)
'headgear given to oscar' is the wordplay.
'headgear' becomes 'cap' (cap is a kind of headgear).
'given to' means one lot of letters go next to another.
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'cap'+'o'='CAPO'
(Other definitions for capo that I've seen before include "Leader of gang" , "Head honcho in Cosa Nostra" , "Movable bridge" , "crime boss" , "Mafia boss" .)