Outlaw musicians stealing equipment (7)
I believe the answer is:
brigand
'outlaw' is the definition.
(brigand is a kind of outlaw)
'musicians stealing equipment' is the wordplay.
'musicians' becomes 'band' (group of musicians).
'stealing' is an insertion indicator.
'equipment' becomes 'rig' (rig is a kind of equipment).
'band' placed around 'rig' is 'BRIGAND'.
(Other definitions for brigand that I've seen before include "desperado" , "Marauder" , "Robber in wild places" , "Criminal" , "Robber in a gang" .)