have a clue
not have a clue
1. To not have even a remote grasp or understanding of something; to be hopelessly confused or ignorant about something. You'd expect the average citizen to struggle to explain the workings of government, but now it seems like even most politicians don't have a clue! You don't have a clue about how to talk to people, do you? When it comes to trigonometry, I just don't have a clue.
2. To be completely unaware of something. A: "Do you think Paul suspects that we're having a surprise party for him? B: "No, he doesn't have a clue!"
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
have a clue (about something)
Fig. to know anything about something; to have even a hint about someone or something. (Usually negative.) I don't have a clue about where to start looking for Jim. Why do you think I have a clue about Tom's disappearance?
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.