Celia changes her name (5)
I believe the answer is:
alice
'her name' is the definition.
'celia changes' is the wordplay.
'changes' indicates anagramming the letters.
'celia' anagrammed gives 'ALICE'.
(Other definitions for alice that I've seen before include "Carroll heroine" , "Wonderland heroine" , "Lewis Carroll's heroine" , "Miss Liddell" , "A Town Like - - (novel/film)" .)