Definition of “clue” - Learner’s Dictionary

clue

noun [ C ] us uk /kluː/
The police are still searching for clues as to who committed the murder.Police are hoping that the weapon may hold some clues as to the identity of the killer.The police scoured the surrounding countryside for possible clues.I'll never guess the answer if you don't give me a clue.Give me a clue, then, and I'll try to guess.

B2 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

B2 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” from the Cambridge Learner's Dictionary © Cambridge University Press)