I explain model being kept by former lover without much money (9)
I believe the answer is:
expositor
'i explain' is the definition.
(to exposit is to explain things)
'model being kept by former lover without much money' is the wordplay.
'model' becomes 'sit' (e.g. for a painting).
'being kept by' indicates putting letters inside.
'former lover' becomes 'ex' (ex-lover).
'without much money' becomes 'poor' (financially poor).
'ex'+'poor'='expoor'
'sit' going inside 'expoor' is 'EXPOSITOR'.
(Other definitions for expositor that I've seen before include "One who interprets" , "Explainer of complicated ideas or theories" , "interpreter" , "One setting out" , "One explains" .)