Bent on getting back the money (5)
I believe the answer is:
notes
'the money' is the definition.
(thesaurus)
'bent on getting back' is the wordplay.
'bent' becomes 'set' ('set' can be a synonym of 'bent').
'getting back' is a reversal indicator.
'set'+'on'='seton'
'seton' reversed gives 'NOTES'.
(Other definitions for notes that I've seen before include "registers?" , "output from musicians" , "Memos; observes" , "Observes; short comments" , "Brief letters; money" .)