Smelly stuff next to one revolting prison (7)
I believe the answer is:
dungeon
'prison' is the definition.
(a dungeon is a prison cell)
'smelly stuff next to one revolting' is the wordplay.
'smelly stuff' becomes 'dung' (dung smells bad).
'next to' says to put letters next to each other.
'revolting' is an anagram indicator.
'one' with letters rearranged gives 'eon'.
'dung'+'eon'='DUNGEON'
(Other definitions for dungeon that I've seen before include "Dark prison cell" , "Prison cell, often underground" , "Eg, the Black Hole of Calcutta" , "old prison" , "Place of confinement underground" .)