If a thing or person is Clapped Out it is exhausted and unable to continue. The origin of the phrase lies in the sport of hare coursing, a centuries-old practice and the forerunner of today's greyhound racing. A pair of greyhounds would be let loose after a hare in a race to catch it. Often the chase could take a long time and the hare, in an attempt to catch its breath, would find a chance to stop and sit up on its haunches. With its fear and exhaustion being so great and its breathing so heavy, the hare's chest would heave in and out, making the front legs move backwards and forwards in time, giving the appearance of clapping. And so, this is how the phrase “clapped out” entered the English language.