End of story on the radio (4)
I believe the answer is:
tail
'end' is the definition.
(tail is a kind of end)
'story on the radio' is the wordplay.
'story' becomes 'tale' ('tale' can be a synonym of 'story').
'on the radio' shows a homophone (sound like).
'tale' sounds like 'TAIL'.
'of' is the link.
(Other definitions for tail that I've seen before include "Follow; end part" , "Rear appendage of animal" , "Follow - dog" , "Private investigator" , "Dog - end" .)