I’d get a piece of green future wood and a rasp...... and start rasping yourself a pile of future wood dust/grit. I’d take that dust and mix it with tightbond 3 and pack it into the hole, trying my best to keep it nice and clean and maybe just a shade above level with the mouth of the hole to allow for sanding flush before finishing. Probably want to mix it to the point where it almost seems like more green dust than glue...... less like a paste and more like a clumpy wood filler.