have a clue
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?
not have a clue(informal)
to have no knowledge of or no information about something 'How much do houses cost in Yorkshire?' 'I haven't got a clue.' (often + about ) Internet researchers in the 1980s didn't have a clue about the exciting online landscapes of the future.