First course at Pisa, not soup (9)
I believe the answer is:
antipasto
'first course' is the definition.
(I know this)
'at pisa not soup' is the wordplay.
'soup' indicates an anagram.
'at'+'pisa'+'not'='atpisanot'
'atpisanot' anagrammed gives 'ANTIPASTO'.
(Other definitions for antipasto that I've seen before include "Italian dish" , "Italian hors d'oeuvre" , "Italian appetiser" , "hors-d'oeuvre" , "Appetizers in an Italian meal" .)