The public should be 'clued in' to what's happening. [=should be told about what's happening]
He doesn't have a 'clue' when it comes to fixing cars. [=he knows nothing about fixing cars]
He's totally 'clued in on' [=he knows a lot about] the latest computer developments.
(..) l've done the background on this woman... ..back to the 's when she was working as an actress. An actress ! There's your first clue, Sherlock ! Her name was Rose Dawson back then. She marries a guy named Calvert. They move to Cedar Rapids and have kids. Now Calvert's dead, and Cedar Rapids, too. (..)1997 Titanic