Rising LA rents increase continually (6)
I believe the answer is:
spiral
'increase continually' is the definition.
(as in spiralling debts)
'rising la rents' is the wordplay.
'rising' says the letters should be written in reverse (in a down clue, letters go up).
'rents' becomes 'rips' ('rip' can be a synonym of 'rent').
'la'+'rips'='larips'
'larips' in reverse letter order is 'SPIRAL'.
(Other definitions for spiral that I've seen before include "Ever widening curve" , "Winding curve" , "Sort of staircase (could be vicious?)" , "Shape of coil or helix" , "Sir, pal inds in continuous loops" .)