When struck, she's apt to flare up (5)

I believe the answer is:
vesta
'flare up' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'when struck she's apt' is the wordplay.
I cannot really see how this works, but
'she' could be 'esta' and 'esta' is located in the answer.
A single letter 'v' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'to' is the link.
Can you help me to learn more?
(Other definitions for vesta that I've seen before include "Asteroid; goddess; match" , "Stave (anag.)" , "heavenly body" , "Roman goddess of the hearth" , "Roman goddess; match" .)
