DuckCorp Dico

Found one definition

1.                 From The Collaborative International Dictionary of English v.0.48:
                   
   
   
                   
                     
   Clacker \Clack"er\, n.
      1. One who clacks; that which clacks; especially, the clapper
         of a mill.
         [1913 Webster]
      2. A claqueur. See Claqueur.
         [1913 Webster]