Ringer

Noun

 * 1) Someone who rings, especially a bell ringer.
 * 2) * 1863, Jean Ingelow, High Tide on the Coast of Lincolnshire,
 * Pull, if ye never pull'd before;
 * Good ringers, pull your best," quoth he.

Noun

 * 1) In the game of horseshoes, when the horseshoe lands around the pole.

Noun

 * 1) A person highly proficient at a skill or sport who is brought in, often fraudulently, to supplement a team.
 * 2) A person, animal, or entity which resembles another so closely as to be taken for the other.  (Now usually in the phrase dead ringer)
 * 3) A person with orange or red hair, often used as an insult.

Derived terms

 * dead ringer

Noun

 * 1)  A top performer
 * 2)  A stockman; a drover

Thesaurus
agent, alternate, alternative, analogy, backup, blagueur, bluff, bluffer, change, changeling, charlatan, comparison, copy, counterfeit, deputy, double, dummy, equal, equivalent, ersatz, exchange, fake, faker, fill-in, fourflusher, fraud, ghost, ghostwriter, humbug, imitation, impersonator, impostor, locum tenens, makeshift, malingerer, metaphor, metonymy, mountebank, next best thing, personnel, phony, picture, pinch hitter, portrait, poser, poseur, pretender, proxy, quack, quacksalver, quackster, relief, replacement, representative, reserves, saltimbanco, second string, secondary, sham, shammer, sign, simulacrum, spares, spit, spitting image, stand-in, sub, substituent, substitute, substitution, succedaneum, superseder, supplanter, surrogate, symbol, synecdoche, third string, token, understudy, utility player, vicar, vice-president, vice-regent

Etymology 1
From ring#Etymology 2: + -er:.

Etymology 2
From ring#Etymology 1:

Etymology 3
Probably from ring the changes:

Anagrams

 * erring