Writer of piece of music on radio (6)
I believe the answer is:
conrad
'writer' is the definition.
(I've seen this before)
'piece of music on radio' is the wordplay.
'piece of' indicates the answer is hidden within the clue.
'CONRAD' can be found hidden inside 'music on radio'.
'of' acts as a link.
(Other definitions for conrad that I've seen before include "Joseph --, writer (Lord Jim)" , "Joseph --, author" , "Author of Lord Jim" , "Joseph ---, Polish-born novelist" , "Heart of Darkness author" .)