Sinner to dwell to the north, by Slough (3-5)
I believe the answer is:
she-devil
'sinner' is the definition.
Both the answer and definition are singular nouns.
Perhaps they are linked in a way I don't understand?
'dwell to the north by slough' is the wordplay.
'dwell' becomes 'live' (synonyms).
'to the north' says the letters should be written backwards (in a down clue, letters go up or 'northward').
'by' says to put letters next to each other.
'slough' becomes 'shed' (both can mean to remove or lose).
'live' backwards is 'evil'.
'evil' put after 'shed' is 'SHE-DEVIL'.
'to' is the link.
Can you help me to learn more?
(Other definitions for she-devil that I've seen before include "woman like Lilith" , "Malicious and spiteful woman" .)