Left group, one featured in commercial (9)
I believe the answer is:
abandoned
'left' is the definition.
(abandoning is a kind of leaving)
'group one featured in commercial' is the wordplay.
'group' becomes 'band' (band is a kind of group).
'featured in' is an insertion indicator.
'commercial' becomes 'ad'.
'band'+'one'='bandone'
'bandone' placed inside 'ad' is 'ABANDONED'.
(Other definitions for abandoned that I've seen before include "Left forlorn" , "Derelict, deserted" , "Unrestrained" , "Rejected" , "Wild" .)