Sun affected rascal (5)
I believe the answer is:
scamp
'rascal' is the definition.
('scamp' can be a synonym of 'rascal')
'sun affected' is the wordplay.
'sun' becomes 's'.
'affected' becomes 'camp' (I've seen this before).
's'+'camp'='SCAMP'
(Other definitions for scamp that I've seen before include "Little Devil" , "Impish child" , "Troublemaker" , "Tearaway" , "Scoundrel" .)