Article with advice regarding a cocktail snack (9)
I believe the answer is:
antipasto
'a cocktail snack' is the definition.
'article with advice regarding' is the wordplay.
'article' becomes 'an' (indefinite article).
'with' means one lot of letters go next to another.
'advice' becomes 'tip' (I've seen this before).
'regarding' becomes 'asto'.
'an'+'tip'+'asto'='ANTIPASTO'
(Other definitions for antipasto that I've seen before include "dishes" , "first course" , "Italian food" , "Appetiser, starter" , "Italian hors d'oeuvre" .)