___ knows?

WHO?

This phrase is often used when questioning someone's knowledge or making a sarcastic remark about uncertainty—think of it as the start of a rhetorical question.

This clue plays on the classic phrase "Who knows?"—a common way to say "I don’t have the answer." The blank is filled with "WHO," turning the clue into a question that literally asks "Who knows?" while also hinting at the answer itself. It’s a self-referential trick where the answer is hidden in plain sight within the clue’s wording.