A bit silly? Well, no! (3)
I believe the answer is:
Here is my best explanation:
'no' is the definition.
Both the answer and definition are adjectives. Maybe they are linked in a way I don't understand?
'a bit silly? well' is the wordplay.
'a bit' indicates a hidden word (the answer is formed by a bit of the clue).
'ILL' can be found hidden inside 'silly well'.