Those in the money? (4)
I believe the answer is:
them
'those' is the definition.
'the money?' is the wordplay.
'money?' becomes 'm' (abbreviation used in economics).
'the'+'m'='THEM'
'in' acts as a link.
(Other definitions for them that I've seen before include "Certainly not us, the other lot" , "Let -- eat cake" , "people objectively" , "Perhaps, the Opposition" , "(To/from) those people" .)