I repaired one about 3 months ago with even more shattering. First I removed the insert. I then used round toothpicks to keep the pieces spread open while I applied Gorilla Glue to the wood. (Be sure the wood is wet with water first or the Gorilla Glue will not work properly.) I then removed the toothpicks, and clamped it all together with rubber bands and let it set a day. I then reinstalled the insert, cut the rubber bands off with a razor, and installed a linen reinforced joint collar. After sanding, I did a quick thin CA finish. The repair was barely visible when I was finished. My customer uses it daily with no change to the hit whatsoever according to him. Wear gloves when using the Gorilla Glue as it can get quite messy.
Also be sure to dry fit the insert to make sure everything is still straight. In my case it was, but it may require plugging and retapping for the insert.
Good luck.