Forbidding the revision of rents (5)
I believe the answer is:
stern
'forbidding' is the definition.
('stern' can be a synonym of 'forbidding')
'the revision of rents' is the wordplay.
'the revision of' indicates anagramming the letters.
'rents' with letters rearranged gives 'STERN'.
(Other definitions for stern that I've seen before include "Severe part of the ship?" , "Harsh at the back of the ship" , "Grave; rear" , "Forbidding in aspect" , "Severe, forbidding" .)