Is to talk to police after money's disappeared (7)
I believe the answer is:
missing
'disappeared' is the definition.
(thesaurus)
'is to talk to police after money's' is the wordplay.
'to talk to police' becomes 'sing' (sing can mean to act as an informant).
'after' says to put letters next to each other.
'money' becomes 'm' (abbreviation in economics).
'is'+'sing'='issing'
'issing' after 'm' is 'MISSING'.
(Other definitions for missing that I've seen before include "Not to be found" , "Absent with location unknown" , "Lost without" .)