Green’s Dictionary of Slang

Dagger-ale n.

[the Dagger, a low tavern sited in Holborn; thus such food as Dagger-pie, Dagger-frumety, sold at the tavern]

very cheap ale.

[UK]U. Fulwell Art of Flattery 6th dialogue 27: This thy description of dagger ale augmenteth my thirst vntill I taste thereof.
John Taylor Wanderings to see Wonders of West 24: There was [...] stong beer and dagger ale, land flesh and sea fish in plenty.