A weak profligate spendthrift, the squire of the company; one who pays the whole reckoning, or treats the company, called standing squire.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
See also the definition in Nathan Bailey's 1736 dictionary of canting and thieving slang.
Squint-a-pipes * SquirishNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes