noun

• (sewing) A pounding block.
• (ice hockey) A slapshot
• (cinematography) The hinged part of a clapperboard, used to synchronise images and soundtrack, or the clapperboard itself.
• (slang) A person's tongue.
  "Emilia 'tis true could use her clapper with great Dexterity, but he had the same advantages against her, which this had against him; Olimpia 's Tongue was also well hung but she ever had reason on her side, which he with reason could never either blame or oppose, and by both these came his Fortune: […]"

verb

• (transitive) To ring a bell by pulling a rope attached to the clapper.
  "It is still necessary to warn clergymen against allowing the lazy and pernicious practice of 'clappering,' i.e. tying the bell-rope to the clapper, and pulling it instead of the bell."

noun

• (obsolete) A rabbit burrow.
  "Poore cunnie so bagged, Is soone overlagged Plash burrow, set clapper, For dog is a snapper"