Crossword Genius

Endless task given to a learner associated with singing (6)

Ross

I believe the answer is:

choral

'singing' is the definition.
(thesaurus)

'endless task given to a learner associated with' is the wordplay.
'endless' means to remove the last letter.
'task' becomes 'chore' ('chore' can be a synonym of 'task').
'given to' means one lot of letters go next to another.
'learner' becomes 'l'.
'associated with' is a charade indicator (letters next to each other).
'chore' with its final letter taken off is 'chor'.
'chor'+'a'+'l'='CHORAL'

(Other definitions for choral that I've seen before include "Music for groups of singers" , "harmonious society" , "Involving many singers" , "Of a singing group" , "Sung by group of singers" .)

I've seen this clue in The Telegraph.
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