Determined to get the money back (3,2)
I believe the answer is:
set on
'determined' is the definition.
(I've seen this before)
'the money back' is the wordplay.
'the money' becomes 'notes' (I've seen this before).
'back' is a reversal indicator.
'notes' reversed gives 'SET ON'.
'to get' acts as a link.
(Other definitions for set on that I've seen before include "Attack" , "Go" , "Determined" .)