see (someone) in (their) true colours

show (someone) in (their) true colours - to show what someone's real character is, especially when it is unpleasant.

At last he saw her in her true colours as a liar and a cheat.

• clean up somewhere
• clean up your act
• clear as mud
• clear-cut
• clear-eyed
• clear name
• clear out
• clear someone's name
• clear the air
• clear the decks
• clear the way
• clear the way for
• clear the way for someone
• clear the way for something
• clear throat
• clear your name
• clear your throat
• clever clogs
• clever dick
• climbing the walls
• climb into bed with
• climb into bed with someone
• climb on high horse
• climb on your high horse
• cling hang on by fingernails