Rachel's biblical sister (4)
I believe the answer is:
leah
'rachel's biblical sister' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for leah that I've seen before include "Jacob's first wife (Gen. 29)" , "Jacob's first wife (Bible)" , "First wife of Jacob" , "Hale (anag) - wife of Jacob" , "She married Jacob" .)