Nine fish can swim freely with this? (5)
I believe the answer is:
nonet
This could be a double definition.
'nine' is the first definition.
(group of nine musicians)
'fish can swim freely with this?' is the second definition.
The definition suggests a singular noun which matches the answer.
Can you help me to learn more?
(Other definitions for nonet that I've seen before include "Group of singers" , "small band" , "Musical composition -- tonne (anag)" , "Tonne (anag.); music for a group" , "Piece of music for nine" .)