I'm great novel detective (7)

I believe the answer is:
maigret
'detective' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for maigret that I've seen before include "Georges Simenon's detective" , "Simenon''s detective-superintendent" , "Simenon's Inspector" , "Policeman" , "Fictional detective" .)