One story’s no good about designated victim (5)

I believe the answer is:

isaac

I'm a little stuck... Click here to teach me more about this clue!

'designated victim' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for isaac that I've seen before include "one almost sacrificed" , "- Newton, Eng. physicist and mathematician" , "Hebrew patriarch" , "Abraham's son" , "Abraham, --, Jacob" .)

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app