Isaac's son given some thesaurus (4)

I believe the answer is:

esau

'isaac's son' is the definition.
(I've seen this before)

'some thesaurus' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'ESAU' is hidden within 'thesaurus'.

'given' is the link.

(Other definitions for esau that I've seen before include "First son of Isaac (Bible)" , "brother done in Bible" , "Elder of the twin sons of Isaac and Rebecca" , "Hairy OT man" , "Rebecca's son" .)

I've seen this clue in The Everyman puzzle in The Observer.

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