Investigator in hustle corrupt (6)
I believe the answer is:
sleuth
'investigator' is the definition.
(I know that sleuth is a type of criminal investigator)
'hustle corrupt' is the wordplay.
'corrupt' indicates an anagram.
'hustle' anagrammed gives 'SLEUTH'.
'in' acts as a link.
(Other definitions for sleuth that I've seen before include "Detective; play and film" , "Track" , "Sherlock Holmes, for example" , "A detective like Sherlock Holmes" , "Hustle for a clever detective like Sherlock" .)