Roughly hustle investigator (6)
I believe the answer is:
sleuth
'investigator' is the definition.
(sleuth is a kind of investigator)
'roughly hustle' is the wordplay.
'roughly' indicates an anagram.
'hustle' with letters rearranged gives 'SLEUTH'.
(Other definitions for sleuth that I've seen before include "Hustle (anag)" , "Bloodhound" , "Sherlock Holmes, for example" , "See detective" , "Olivier/Caine film" .)