Violinist Stern (5)
I believe the answer is:
isaac
'violinist stern' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for isaac that I've seen before include "According to the book, twins' dad" , "Father to Jacob and Esau" , "Father of 21" , "Biblical father of twins" , "one almost sacrificed" .)