Outlaw's sweetheart stealing granny's cash? (8)
I believe the answer is:
banknote
'cash?' is the definition.
(I know that banknote is a type of cash)
'outlaw's sweetheart stealing granny's' is the wordplay.
'outlaw' becomes 'ban' (banning is a kind of outlawing).
'sweetheart' becomes 'e' (the heart/centre of 'sweet').
'stealing' is an insertion indicator.
'granny' becomes 'knot' (I've seen this in another clue).
'ban'+'e'='bane'
'bane' enclosing 'knot' is 'BANKNOTE'.
(Other definitions for banknote that I've seen before include "Money" , "Paper cash" , "Monetary quantity" .)