ringer

noun

1. a horseshoe or quoit thrown so that it encircles the peg
2. such a throw

noun

1. a person or thing that rings a bell, chime, etc.
2. ☆ Slang
   1. a horse, player, etc. fraudulently entered, or substituted for another, in a competition
   2. any substitute
   3. a person or thing very closely resembling another