Debauched type going north from Rouen (4)
I believe the answer is:
roue
'debauched type going' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'north from rouen' is the wordplay.
'north' becomes 'N' (abbreviation).
'from' is a deletion indicator.
'rouen' with 'n' taken away is 'ROUE'.
Can you help me to learn more?
(Other definitions for roue that I've seen before include "One seeking personal gratification" , "Dissipated man" , "Lecherous man" , "Casanova" , "Libertine male" .)