Task to insert a line in hymn tune (7)
I believe the answer is:
chorale
'hymn tune' is the definition.
(I've seen this in another clue)
'task to insert a line' is the wordplay.
'task' becomes 'chore' (synonyms).
'to insert' becomes 'al' (I can't justify this - if you can you should give a lot more credence to this answer).
'a line' is an insertion indicator.
'chore' going around 'al' is 'CHORALE'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for chorale that I've seen before include "Stately hymn tune" , "Lutheran hymn-tune" , "Harmonised hymn tune" , "Composition" , "Psalm or hymn tune" .)