Alternative accepted by such poor singers (6)
I believe the answer is:
chorus
'singers' is the definition.
(chorus can mean a group of singers)
'alternative accepted by such poor' is the wordplay.
'alternative' becomes 'or'.
'accepted by' indicates putting letters inside (inserted letters are accepted).
'poor' indicates anagramming the letters.
'such' anagrammed gives 'chus'.
'or' placed inside 'chus' is 'CHORUS'.
(Other definitions for chorus that I've seen before include "Band of singers and dancers" , "Group singing together" , "Group of singers as in musicals" , "Group of voices" , "Dramatic team" .)