Represent naughty boy’s smile (9)
I believe the answer is:
symbolise
'represent' is the definition.
('represent'->'symbolize' is in my internal thesaurus and 'ize'->'ise')
'naughty boy's smile' is the wordplay.
'naughty' indicates anagramming the letters.
'boys'+'smile'='boyssmile'
'boyssmile' with letters rearranged gives 'SYMBOLISE'.
(Other definitions for symbolise that I've seen before include "Represent or be a sign of" , "Represent, stand for" .)