A group of musicians on leave (7)
I believe the answer is:
abandon
'leave' is the definition.
(abandoning is a kind of leaving)
'a group of musicians on' is the wordplay.
'group of musicians' becomes 'band' (I've seen this before).
'a'+'band'+'on'='ABANDON'
(Other definitions for abandon that I've seen before include "Completely give up; desert" , "Stop" , "Leave, desert" , "Evacuate; desert" , "ditch" .)