Turn on radio for part played (4)
I believe the answer is:
role
'for part played' is the definition.
I can't judge whether this definition defines the answer.
'turn on radio' is the wordplay.
'turn' becomes 'roll' (roll is a kind of turn).
'on radio' shows a homophone (sound like).
'roll' is a homophone of 'ROLE'.
Can you help me to learn more?
(Other definitions for role that I've seen before include "Playing part" , "Part, portrayal" , "Stage part" , "Impersonation" , "Duty" .)