Unbeliever ate this goulash (7)
I believe the answer is:
atheist
'unbeliever' is the definition.
(atheist is a kind of unbeliever)
'ate this goulash' is the wordplay.
'goulash' is an anagram indicator (goulash is a type of stew or mixture).
'ate'+'this'='atethis'
'atethis' anagrammed gives 'ATHEIST'.
(Other definitions for atheist that I've seen before include "Someone who denies the existence fo God" , "Unbeliever" , "Person who believes there is no God" , "Person who does not believe in existence of a god" , "Godless person" .)