Bishop questioning extortionist, a fishy character (7,5)
I believe the answer is:
basking shark
'a fishy character' is the definition.
(basking shark is a kind of fish)
'bishop questioning extortionist' is the wordplay.
'bishop' becomes 'B' (chess abbreviation).
'questioning' becomes 'asking' (I've seen this before).
'extortionist' becomes 'shark' (as in a loan shark).
'b'+'asking'+'shark'='BASKING SHARK'
(Other definitions for basking shark that I've seen before include "Swimmer afloat" , "marine creature" , "Large fish that often floats on the surface of the sea" , "Large unthreatening fish" , "Plankton-eater" .)