On the radio a contender's coming (7)
I believe the answer is:
arrival
'coming' is the definition.
(I know that coming can be written as arrival)
'on the radio a contender's' is the wordplay.
'on the radio' shows a homophone (sound like).
'contender' becomes 'rival' (synonyms).
'a'+'rival'='arival'
'arival' is a homophone of 'ARRIVAL'.
(Other definitions for arrival that I've seen before include "Someone who's just come" , "Appearance, entrance" , "The reaching of one's destination" , "Achievement of destination" , "Appearance (at a place)" .)