The money Monica shiftily concealed (4)
I believe the answer is:
cash
'the money' is the definition.
(cash is a type of money)
'monica shiftily concealed' is the wordplay.
'concealed' says the answer is hidden in the clue.
'CASH' is hidden in the letters of 'monica shiftily'.
(Other definitions for cash that I've seen before include "Spondulicks" , "Ready money" , "Brass" , "Till" , ""Readies"" .)