The Stones' great composer (6)
I believe the answer is:
gravel
'the stones' great composer' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'great composer' is the wordplay.
'great' becomes 'g' (this could be a standard abbreviation which I don't know about).
'composer' becomes 'ravel' (I've seen this before).
'g'+'ravel'='GRAVEL'
Can you help me to learn more?
(Other definitions for gravel that I've seen before include "Small rounded stones" , "Small fragments of rock" , "Mass of small stones" , "Loose fragments of rock" , "Shingle" .)