A bit of silliness in style (5)
I believe the answer is:
Here is my best explanation:
'style' is the definition.
'a bit of silliness in' is the wordplay.
'a bit of' indicates a hidden word (I've seen 'a bit' mean this (the answer is formed by a bit of the clue)).
'LINES' can be found hidden inside 'silliness in'.