Reportedly, country music was his forte (7)
I believe the answer is:
britten
'music was his forte' is the definition.
The definition suggests a singular noun which matches the answer.
'reportedly country' is the wordplay.
'reportedly' indicates a 'sounds like' (homophone) clue.
'country' becomes 'Britain' (Britain is an example).
'britain' sounds like 'BRITTEN'.
(Other definitions for britten that I've seen before include "Billy Budd composer" , "British composer associated with Aldeburgh" , "Composer of Peter Grimes" , "Composer born 1913" , "See 8" .)