Once again begin to relax by painting, perhaps (7)
I believe the answer is:
restart
'once again begin' is the definition.
('start' can be a synonym for 'begin' so perhaps 'restart' is OK for 'once again begin')
'relax by painting perhaps' is the wordplay.
'relax' becomes 'rest' (to relax is to have a rest).
'by' is a charade indicator (letters next to each other).
'painting perhaps' becomes 'art' (painting is a kind of art).
'rest'+'art'='RESTART'
'to' acts as a link.
(Other definitions for restart that I've seen before include "Commence again" , "Jumping the gun will mean" , "Resume" , "launch again" , "begin afresh" .)