Formal state banquet’s second prepared with spring vegetables (9)
I believe the answer is:
Here is my best explanation:
'prepared with spring vegetables' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'formal state banquet's second' is the wordplay.
'formal' becomes 'prim' (I've seen this in other clues).
'state' becomes 'aver' (I've seen this before).
'banquet's second' becomes 'a' (2nd letter of 'banquet').
(Other definitions for primavera that I've seen before include "picture of Botticelli", "graceful painting" and "Botticelli painting".)