Less poor (6)
I believe the answer is:
richer
'less poor' is the definition.
('rich' can be the opposite of 'poor' so perhaps 'richer' is reasonable for 'less poor')
This is the entire clue.
(Other definitions for richer that I've seen before include "More wealthy" , "More affluent" , "Wealthier" , "More well-off" , "Having more wealth" .)