Drastically reduce rent (5)
I believe the answer is:
slash
This clue is a double definition.
'drastically reduce' is the first definition.
(I've seen this in another clue)
'rent' is the second definition.
(I've seen this before)
(Other definitions for slash that I've seen before include "Violently cut" , "Punctuation mark" , "rent" , "something between a month and a year" , "Cut as with a sword - /" .)