Apparently folks think it might be something made from apples. This guy talks about it and suggests using this recipe. He uses it in making a pre-Prohibition drink called the St. Croix Crusta:
1 dash bitters (Ango works fine; it originally called for Boker’s)
1 barspoon lemon juice
1 barspoon maraschino liqueur
¼ oz orchard syrup
1½ oz white St. Croix rum (I used Barbancourt white, as it’s what I had available)
Using a vegetable peeler, peel a lemon in one long spiral. Run a cut lemon around a pony-style glass fairly far down the edge and dip in sugar. Place the entire lemon peel in the glass, maintaining its shape as best as possible. Shake all ingredients (or stir; I’m not arguing over this one) over ice and strain into the glass.
He has a picture posted of a female friend who looks as though she is enjoying the result.