US city rents in recession increase continually (6)
I believe the answer is:
spiral
'increase continually' is the definition.
(as in spiralling debts)
'us city rents in recession' is the wordplay.
'us city' becomes 'LA' (Los Angeles).
'rents' becomes 'rips' ('rip' can be a synonym of 'rent').
'in recession' is a reversal indicator (letters recede or go back).
'la'+'rips'='larips'
'larips' reversed gives 'SPIRAL'.
(Other definitions for spiral that I've seen before include "Shape of coil or helix" , "Mushroom" , "Shape of many galaxies" , "Corkscrew curve" , "Shape of a coiled spring" .)