Drawn or worked by a single horse. / (by extension) Small, insignificant.

(US, idiomatic) A very small town, especially one of a rural nature and/or offering very few or no attractions.

plural of one-horse town

(horse racing, informal) A horse race in which a single horse takes such a considerable lead that the other horses are no longer contenders to win.

plural of one-horse race

plural of one-horse lawyer

A lawyer who has only worked in a small town, lacking the experience and sophistication of more prominent lawyers.

(idiomatic) To be patient; to wait.

present participle of hold one's horses

simple past tense and past participle of hold one's horses