English puzzle is hell! (6)
I believe the answer is:
erebus
'is hell' is the definition.
(thesaurus)
'english puzzle' is the wordplay.
'english' becomes 'e' (abbreviation).
'puzzle' becomes 'rebus' (I've seen this before).
'e'+'rebus'='EREBUS'
(Other definitions for erebus that I've seen before include "It's hellish dark" , "The abode of the dead" , "Antarctic volcano; region between earth and Hades" , "Level of the underworld" , "Dark and gloomy cavern between earth and Hades." .)