Myra changes her name (4)
I believe the answer is:
mary
'her name' is the definition.
'myra changes' is the wordplay.
'changes' indicates an anagram.
'myra' with letters rearranged gives 'MARY'.
(Other definitions for mary that I've seen before include "Person venerated by Christians" , "could be Wesley" , "feature of 21/23 [NATIVITY SCENE]" , "Successor to Edward VI" , "Disney film with Julie Andrews" .)