not have a clue

Have no idea or inkling about something, as in Jane doesn't have a clue as to why John won't call her, or Do you know what's wrong with the boiler?—No, I haven't a clue. This usage was first recorded in 1928.

Words nearby not have a clue

not give a damn, not give someone the time of day, not half bad, no thanks to, not have a bean, not have a clue, not have an earthly chance, not have anything on, not have it, not have one's heart in it, not have the heart to
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.