Applesauce- an expletive same as horsefeathers, As in "Ah applesauce!"
Horsefeathers - an expletive ; same usage as applesauce
Well, THAT's not helpful.
Will Rogers wrote in The Illiterate Digest (1924), "I tell you Folks, all Politics is Apple Sauce."
One of the definitions in Urban Dictionary (the clean meaning) is "An early 90s slang word for 'ridiculous' or 'nonsense'." Well, no, it's from much earlier, but at least this narrative provides something more than a circular definition.
Shot in the Dark Mysteries has posted 1920s Slang Terms and Definitions:
Applesauce: A mild curse, like “darn” (also, "Horsefeathers!")
The term had gotten new life from the US Supreme Court, of all places. From the Washington Post:
Justice Antonin Scalia clearly gets a kick out of writing his pointed, colorful dissents for the Supreme Court, and his minority opinion in [2015's] King v. Burwell decision is no exception.
With characteristic vigor, the panel’s most conservative justice lashed out at his colleagues for concluding that the Affordable Care Act allows people on state insurance exchanges established by the federal government to receive subsidies. The opinion offers several new candidates for a master list of Scalia’s best turns-of-phrase, which should be published as a book as far as we are concerned. One example: the majority’s reasoning? “Pure applesauce,” he wrote.
A recent clue on the game show JEOPARDY! in the category Compound Words was this: "Nonsense, or a pippin stewed to a pulp, sweetened & spiced." No one got this $2000 clue.
Incidentally, my father-in-law makes very good apple sauce!