Decreased rent, to Spooner's eternal torment (8)
I believe the answer is:
hellfire
'torment' is the definition.
(I have seen 'endless torment' mean 'hellfire' so perhaps 'torment' could also mean 'hellfire')
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for hellfire that I've seen before include "endless torment" , "Punishment in a very hot place" , "Eternal punishment" , "Infernal flames" , "Flames of damnation" .)