Fast food item (12)
'fast food item' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cheeseburger that I've seen before include "Fast food product" , "Fast food item" , "Fast food snack" , "Fast food -- begs cure here (anag)" , "filled roll" .)
(Other definitions for pizza that I've seen before include "round dish" , "Italian dough based dish" , "Italian open pie made with thin dough" , "Eg, calzone" , "Common fast food" .)
(Other definitions for hot dog that I've seen before include "grub?" , "Sausage in bread roll for thermal canine" , "food from a stand?" , "Sausage snack" , "Sausage in breae roll" .)