Biblical son of Isaac (4)
I believe the answer is:
esau
'biblical son of isaac' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for esau that I've seen before include "Son of Isaac, brother to Jacob (Bible)" , "character in the Bible" , "Cunning hunter" , "Biblical brother to Jacob" , "Hairy OT character" .)