Study awful rot written about church music (8)
I believe the answer is:
concerto
'music' is the definition.
(concerto is a kind of music)
'study awful rot written about church' is the wordplay.
'study' becomes 'con' (I've seen this before).
'awful' is an anagram indicator.
'written about' means one lot of letters goes inside another.
'church' becomes 'ce' (abbreviation for Church of England).
'rot' is an anagram of 'rto'.
'rto' going around 'ce' is 'certo'.
'con'+'certo'='CONCERTO'
(Other definitions for concerto that I've seen before include "Orchestral work for solo instrument" , "Work for soloist and orchestra" , "Musical composition" , "piece of music" , "Piece for soloist and orchestra" .)