Upset a top saint for starter (9)
I believe the answer is:
antipasto
'for starter' is the definition.
(I've seen this before)
'upset a top saint' is the wordplay.
'upset' indicates an anagram.
'a'+'top'+'saint'='atopsaint'
'atopsaint' is an anagram of 'ANTIPASTO'.
(Other definitions for antipasto that I've seen before include "Italian hors d'oeuvres" , "Italian dish" , "hors-d'oeuvre" , "Italian hors d'oeuvre" , "garnish!" .)