Cook raving about Eastern condiment (7)
I believe the answer is:
vinegar
'condiment' is the definition.
(vinegar is a kind of condiment)
'cook raving about eastern' is the wordplay.
'cook' indicates an anagram.
'about' is an insertion indicator.
'eastern' becomes 'e'.
'raving' with letters rearranged gives 'vingar'.
'vingar' enclosing 'e' is 'VINEGAR'.
(Other definitions for vinegar that I've seen before include "Sour stuff" , "Condiment - bad temper" , "Pickling condiment" , "Healer with brown paper" , "Peevishness" .)