Old Rose changes her name (7)
I believe the answer is:
dolores
'her name' is the definition.
'old rose changes' is the wordplay.
'changes' indicates anagramming the letters.
'old'+'rose'='oldrose'
'oldrose' with letters rearranged gives 'DOLORES'.
(Other definitions for dolores that I've seen before include "Lady" , "Female" , "Old sore about girl" .)