With all players expressing disapproval, sending off no good (5)
I believe the answer is:
tutti
'with all players' is the definition.
(musical term)
'disapproval sending off no good' is the wordplay.
I cannot really see how this works, but
'disapproval' could be 'tut' (I have seen 'Express disapproval' mean 'tut' so perhaps 'disapproval' could also mean 'tut') and 'tut' is present in the answer.
The remaining letters 'ti' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'expressing' acts as a link.
Can you help me to learn more?
(Other definitions for tutti that I've seen before include "Passage using all instruments" , "Musical instruction for all instruments to play" , "with instruments and singers together" , "All (stage direction)" , "Composer of Carmina Burana" .)