Fellow cutting crime is one wanting a good time (8)
I believe the answer is:
hedonist
'one wanting a good time' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'fellow cutting crime' is the wordplay.
'fellow' becomes 'don' (both can mean an academic).
'cutting' means one lot of letters goes inside another (some letters cut their way into a word).
'crime' becomes 'heist' (heist is a kind of crime).
'don' placed inside 'heist' is 'HEDONIST'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for hedonist that I've seen before include "One who believes in pleasure" , "sybarite" , "Extreme pleasure-seeker" , "For whom pleasure is the chief god" , "one enjoying himself" .)