The CISSP exam does not ask you to define Clark-Wilson.

It gives you a scenario:

"A bank needs to ensure that financial transactions are processed correctly and that no single employee can manipulate records without detection."

Then it asks which security model applies.

If you memorized the definition, you might get it right.

If you understand the problem it solves - separation of duties, integrity of transactions, controlled access - you will get it right every time.