Queen Elsa's sister (4)
I believe the answer is:
anna
'queen elsa's sister' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for anna that I've seen before include "Massey, Sewell or Karenina" , "- - Ford (TV)" , "Dame -- Neagle" , "Old Indian coin - girl's name" , "Unit of length" .)