Nine compositions? (6)
I believe the answer is:
nonets
'nine compositions?' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'nine compositions?' is the wordplay.
'nine' becomes 'nonet' (group of nine musicians).
'compositions?' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'nonet'+'s'='NONETS'
Can you help me to learn more?
(Other definitions for nonets that I've seen before include "Compositions for nine performers" , "musical pieces" , "Group of players" , "Pieces of music for nine instruments or voices" , "Pieces of music for groups of nine" .)