Asleep when she got back in (4)
I believe the answer is:
elsa
If this is the answer I cannot explain how the clue works.
Can you help me to learn more?
(Other definitions for elsa that I've seen before include "Girl" , "Big cat" , "___ Schiaparelli, Italian-born French fashion designer d. 1973" , "Famous lioness" , "Lioness (born free in Kenya)" .)