She’s in a grave state (5)
I believe the answer is:
vesta
'she's' is the definition.
Both the answer and definition are singular nouns.
Perhaps you can see an association between them that I can't see?
'in a grave state' is the wordplay.
'in' indicates a hidden word.
'VESTA' is hidden within 'grave state'.
Can you help me to learn more?
(Other definitions for vesta that I've seen before include "Hearth goddess; a match" , "Roman goddess of the hearth" , "Roman goddess; match" , "heavenly body" , "Stave (anag.)" .)