Success in hoax investigation (8)
I believe the answer is:
conquest
'success' is the definition.
(I know that conquest is a type of success)
'hoax investigation' is the wordplay.
'hoax' becomes 'con'.
'investigation' becomes 'quest'.
'con'+'quest'='CONQUEST'
'in' is the link.
(Other definitions for conquest that I've seen before include "hostile takeover" , "Catch" , "The subjugation and assumption of control by military force" , "Victory by force" , "Vanquishment" .)