Chart roles unclear regarding much classical music (10)
I believe the answer is:
orchestral
'regarding much classical music' is the definition.
'chart roles unclear' is the wordplay.
'unclear' is an anagram indicator.
'chart'+'roles'='chartroles'
'chartroles' with letters rearranged gives 'ORCHESTRAL'.
(Other definitions for orchestral that I've seen before include "For a large group of musicians - her car slot (anag)" , "Unlike chorales" , "Using a large group of instruments" , "for the band" , "Sort of music" .)