Rock enjoyable on the radio (6)
I believe the answer is:
gneiss
'rock' is the definition.
(gneiss is a kind of rock)
'enjoyable on the radio' is the wordplay.
'enjoyable' becomes 'nice' (I've seen this before).
'on the radio' indicates a 'sounds like' (homophone) clue.
'nice' is a homophone of 'GNEISS'.
(Other definitions for gneiss that I've seen before include "Coarse-grained rock; sounds like agreeable" , "Metamorphic rock" .)