Cornelia changes her name (8)
I believe the answer is:
caroline
'her name' is the definition.
'cornelia changes' is the wordplay.
'changes' is an anagram indicator.
'cornelia' with letters rearranged gives 'CAROLINE'.
(Other definitions for caroline that I've seen before include "No eclair for this girl" , "Lady - Lamb, Lord Byron's lover" , "Girl's name - relating to Stuart king" .)