Purse discovered, nothing missing (4)
I believe the answer is:
fund
'purse' is the definition.
(thesaurus)
'discovered nothing missing' is the wordplay.
'discovered' becomes 'found' (to discover is to find).
'nothing' becomes 'O' (looks like zero - 0).
'missing' is a deletion indicator.
'found' with 'o' taken away is 'FUND'.
(Other definitions for fund that I've seen before include "Sum of money set aside for a purpose" , "Reserve of money for future use" , "Sponsor" , "Monetary resources" , "Capitalize" .)