Group of musicians not touring Tyneside (5)
I believe the answer is:
nonet
'group of musicians' is the definition.
(a nonet requires nine musicians)
'not touring tyneside' is the wordplay.
'touring' means one lot of letters goes inside another (touring can mean going round).
'tyneside' becomes 'ne' (region in North East of England).
'not' placed around 'ne' is 'NONET'.
(Other definitions for nonet that I've seen before include "Piece for nine musicians" , "Musical group" , "musical piece" , "Music for nine instruments or voices" , "baseball team" .)