clue · noun C /kluː/
clue
B2 a sign or some information that helps you to solve a problem or answer a question
Dictionary examples:
Police are searching the area for clues to the murder.
Police are still looking for clues in their search for the missing girl.
I'm never going to guess the answer if you don't give me a clue.
Learner example:
They found it and they started looking for more clues. (First Certificate in English; B2; Spanish)
not have a clue
B2 to be completely unable to guess, understand, or deal with something
Dictionary example:
I don't have a clue what you're talking about.
Learner example:
I haven't a clue about it. (First Certificate in English; B2; Japanese)
