Stones German composer (6)
I believe the answer is:
gravel
'stones' is the definition.
(I've seen this in another clue)
'german composer' is the wordplay.
'german' becomes 'g' (abbreviation).
'composer' becomes 'ravel' (Maurice Ravel).
'g'+'ravel'='GRAVEL'
(Other definitions for gravel that I've seen before include "Coarse sand mixed with small stones" , "Grit" , "Shingle" , "Loose fragments of rock" , "Small rounded stones" .)