Son of Abraham and Sarah, father of Jacob and Esau (5)
I believe the answer is:
isaac
I believe this is a double definition.
'son of abraham and sarah' is the first definition.
(I've seen this in another clue)
'father of jacob and esau' is the second definition.
(I've seen this in another clue)
(Other definitions for isaac that I've seen before include "Sacrificial offering" , "Newton's first name" , "one almost sacrificed" , "According to the book, twins' dad" , "Sir -- Newton, English scientist" .)