He sold his birthright in the sausage factory (4)
I believe the answer is:
esau
'he sold his birthright' is the definition.
(I've seen this in another clue)
'in the sausage factory' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ESAU' is hidden in the letters of 'the sausage factory'.
(Other definitions for esau that I've seen before include "wronged brother" , "Biblical character who sold birthright for pottage" , "He traded his birthright for a mess of pottage" , "Son of Isaac, brother to Jacob (Bible)" , "Brother to Jacob (OT)" .)