Type of hymn or carol he arranged (7)
I believe the answer is:
'type of hymn' is the definition.
'carol he arranged' is the wordplay.
'arranged' indicates anagramming the letters.
'carolhe' with letters rearranged gives 'CHORALE'.
'or' is the link.
(Other definitions for chorale that I've seen before include "Psalm or hymn tune" , "Composition" , "vocal music" , "Harmonised hymn tune" , "Simple hymn tune" .)