Anything such as a naughty bit (5)
I believe the answer is:
aught
'anything' is the definition.
(thesaurus)
'as a naughty bit' is the wordplay.
'bit' indicates a hidden word.
'AUGHT' can be found hidden inside 'as naughty'.
'such' is the link.
(Other definitions for aught that I've seen before include "Emphatically anything" , "Nothing" , "Anything (Shakespearean)" , "Anything at all (archaic)" .)