if something hangs by a thread, it is likely to fail in the near future.

Peace and democracy hang by a thread in this troubled country.

• clean sheet
• clean slate
• clean someone out
• clean sweep
• clean up
• clean up act
• 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