A pun or quibble. To clinch, or to clinch the nail; to confirm an improbable story by another: as, A man swore he drove a tenpenny nail through the moon; a bystander said it was true, for he was on the other side and clinched it.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Climb * ClinkNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes