Crossword clue: What is this?

The answer to the crossword clue "What is this?" is "CLUE." A clue is a hint or piece of information that helps someone solve a puzzle or mystery. In the context of a crossword, each clue leads to a specific answer, guiding players to fill in the correct words. So, when someone asks, "What is this?" they might be looking for a hint, which is exactly what a clue provides.