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.
(..) He's not with us no more. I know this is asking a lot, but do you think there's anyway that we could go... To your house and look around to see if there's any clues for our friend? Absolutely. How else do you think we're gonna get the tiger back anyway? Come on, Champ. I'm sorry? (..)2009 The Hangover
(..) Seriously, how much do you wanna bet? It's like fucked up. That's enough. Alan is seriously worried. Let's not freak him out anymore. I'm sorry, Alan. We'll search the car for clues, and everything's gonna be okay. Oh, shit. I can't see that. I'm not looking. Oh, thank god. It's gonna be alright. (..)2009 The Hangover