Type of hymn or carol he arranged (7)
I believe the answer is:
chorale
'type of hymn' is the definition.
'carol he arranged' is the wordplay.
'arranged' indicates anagramming the letters.
'carol'+'he'='carolhe'
'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" .)