Sonnet performed by groups (6)
I believe the answer is:
nonets
'by groups' is the definition.
'nonets' can be an answer for 'groups' (I've seen this before). I'm unsure of the 'by' bit.
'sonnet performed' is the wordplay.
'performed' indicates anagramming the letters.
'sonnet' with letters rearranged gives 'NONETS'.
Can you help me to learn more?
(Other definitions for nonets that I've seen before include "musical pieces" , "Pieces of music for nine instruments or voices" , "Groups of nine musicians" , "Group of players" , "Compositions for nine performers" .)