Here we have a Gibson Les Paul Standard with a headstock/neck fracture. A really cool guitar but that damage has go to be addressed!
Couple of clamps ought to do the trick. The clear plastic sheet is to keep the glue from getting on the clamps.
After the glue dries and the headstock is solid the cosmetics are addressed. Here is the end result. Now it’s solid, looks good and feels good. I love it when it all works out!