Spouse equal to rent review (7)
I believe the answer is:
partner
'spouse' is the definition.
(I know that partner is a type of spouse)
'equal to rent review' is the wordplay.
'equal' becomes 'par'.
'to' means one lot of letters go next to another.
'review' is a reversal indicator.
'rent' written backwards gives 'tner'.
'par'+'tner'='PARTNER'
(Other definitions for partner that I've seen before include "teammate" , "Associate, in business or private life" , "Colleague, bedfellow" , "Mate or business associate" , "Dancing companion" .)