Cafe's rent low but rising (3,4)
I believe the answer is:
tea room
'cafe's' is the definition.
(I've seen this before)
'rent low but rising' is the wordplay.
'rent' becomes 'tear' (synonyms).
'low' becomes 'moo' (both can mean to make the noise of a cow).
'but rising' shows that the letters should be reversed in order.
'moo' backwards is 'oom'.
'tear'+'oom'='TEA-ROOM'
(Other definitions for tea room that I've seen before include "Small restaurant or cafe" , "Where light refreshments are served" , "Place in which a cuppa is served" , "Place for light refreshments" .)