clue

/kluː/ noun [C]

Definition

› a sign or a piece of information that helps you to solve a problem or answer a question: Police are searching the area for clues to the murder. I can't remember who wrote it. Give me a clue.

not have a clue informal › to be completely unable to guess, understand, or deal with something: [+ question word] I haven't a clue what you're talking about.

(Definition of clue noun from the Cambridge Learner's Dictionary © Cambridge University Press)