Leave a group performing (7)
I believe the answer is:
abandon
'leave' is the definition.
(to abandon is to leave or desert)
'a group performing' is the wordplay.
'group' becomes 'band' (band can mean a group of people).
'performing' becomes 'on' (as in being on stage).
'a'+'band'+'on'='ABANDON'
(Other definitions for abandon that I've seen before include "dump" , "Leave, desert" , "Give up (something) completely" , "Completely give up; desert" , "Kick" .)