Grandson of Abraham (4)
I believe the answer is:
esau
'grandson of abraham' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for esau that I've seen before include "First son of Isaac (Bible)" , "Hairy OT man" , "Biblical brother to Jacob" , "Isaac's hairy son" , "Jacob's twin brother" .)