Loan shark (6)
I believe the answer is:
usurer
'loan shark' is the definition.
(I know that loan shark can be written as usurer)
This is the entire clue.
(Other definitions for usurer that I've seen before include "Lender at an exorbitant rate" , "Grasping money-lender" , "One who charges undue interest" , "Person who charges excessive interest on loan" , "Extortionist" .)