Appetizers rushed over, so messy (4,8)
I believe the answer is:
hors doeuvres
'appetizers' is the definition.
(hors d'oeuvre is a kind of appetizer)
'rushed over so messy' is the wordplay.
'messy' indicates anagramming the letters.
'rushed'+'over'+'so'='rushedoverso'
'rushedoverso' anagrammed gives 'HORS DOEUVRES'.
(Other definitions for hors doeuvres that I've seen before include "Food" , "Antipasto" .)