Green’s Dictionary of Slang

(Irish) drunk.

1922		Joyce Ulysses 404: Digs up near the Mater. Buckled he is. Know his dona? Yup, sartin I do. Full of a dure.
1990		R. Doyle Snapper 89: God, I was buckled.
2001		C. McPherson Port Authority 15: Ducking into Tighe’s [...] and drinking five bottles of Harp. She was buckled by half two.
2009		Berkshire Eagle (Pittsfield, MA) 1 Nov. 29/1: You can’t hold a good Scotsman back when he wants to get [...] buckled, fou, guttered, [...] mortal, pie-eyed [...] plastered [...] steaming, stocious or wrecked.