Apple

Shaking forest trees is the source, which means apples arrive while you are already gathering wood rather than as something you go out to hunt. The buff is the entry-level one and it runs short, so this is a snack you eat while walking somewhere, not a fight preparation.

Its real use is as an ingredient. It feeds Fruit Juice like any other fruit, and it converts into Ambrosia through shimmer, which is a much better buff. Keep a few rather than eating your last one.

It has nothing to do with Apple Pie despite the obvious guess, and the pie wants a completely different ingredient. The tooltip is playing on the old line about keeping the doctor away, with Doctor Bones as the punchline.