Ease off rent increase (3,2)
I believe the answer is:
let up
'ease off' is the definition.
(I know that ease off can be written as let up)
'rent increase' is the wordplay.
'rent' becomes 'let' (I've seen this in another clue).
'increase' becomes 'up' (upping is a kind of increasing).
'let'+'up'='LET-UP'
(Other definitions for let up that I've seen before include "Slackening" , "Pause (during something intense)" , "Relent, relax" , "Pause, respite" , "Abate" .)