She causes Elsie a change of heart (5)
I believe the answer is:
ellie
'she' is the definition.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for ellie that I've seen before include "Name of girl in The Water Babies (Kingsley)" , "woman" , "Little Eleanor" , "Diminutive girl" , "a wake-up call" .)