Condiment in grave trouble (7)
I believe the answer is:
vinegar
'condiment' is the definition.
(vinegar is a kind of condiment)
'in grave trouble' is the wordplay.
'trouble' is an anagram indicator.
'in'+'grave'='ingrave'
'ingrave' with letters rearranged gives 'VINEGAR'.
(Other definitions for vinegar that I've seen before include "Salad dressing" , "Healer with brown paper" , "Sour stuff" , "Pickling medium" , "Ill-temper" .)