Criminal taking fat cut is in the money (9)
I believe the answer is:
larcenist
'criminal' is the definition.
(larcenist is a kind of criminal)
'fat cut is in the money' is the wordplay.
'fat' becomes 'lard' (I've seen this before).
'cut' means to remove the last letter.
'in' is an insertion indicator.
'the money' becomes 'cent' (I've seen this before**).
'lard' with its final letter removed is 'lar'.
'is' inserted into 'cent' is 'cenist'.
'lar'+'cenist'='LARCENIST'
'taking' is the link.
(Other definitions for larcenist that I've seen before include "One takes" , "One criminal" , "Thief" , "Dishonest person" , "Person who takes" .)