Left a musical group with one penny (9)
I believe the answer is:
abandoned
'left' is the definition.
(abandoning is a kind of leaving)
'a musical group with one penny' is the wordplay.
'musical group' becomes 'band' (band is a kind of musical group).
'with' says to put letters next to each other.
'penny' becomes 'd' (abbreviation e.g. Lsd - pounds, shillings, pence).
'a'+'band'+'one'+'d'='ABANDONED'
(Other definitions for abandoned that I've seen before include "Crazy!" , "Quit" , "Dumped" , "Left in the lurch, forsaken" , "Gave up - left - being completely irresponsible" .)