English learning about evil castle (8)
I believe the answer is:
elsinore
'castle' is the definition.
(I've seen this before)
'english learning about evil' is the wordplay.
'english' becomes 'E' (abbreviation as in OED).
'learning' becomes 'lore' (both can mean tradition or knowledge).
'about' indicates putting letters inside.
'evil' becomes 'sin' (synonyms).
'lore' placed around 'sin' is 'lsinore'.
'e'+'lsinore'='ELSINORE'
(Other definitions for elsinore that I've seen before include "Castle in Hamlet" , "Tragic scene" , "Hamlet's place" , "Zealand port" , "haunted castle?" .)