You could try the Torges patch.
First though, I would put thin CA down in there and clamp that glue joint back together. After it was dried, and THAT part was effectively repaired, I'd grind out the area where the grain seperated with a sanding drum of sufficient radius to remove that crack and as much of the surrounding 'strange grain' as possible. Don't grind all the way across the belly if you don't have to. I've had excellent results with those patches... but should admit that I've never had to take one as close to the backing as the glue joint, and yours has already seperated a little there, so I'll be waiting to see how she holds up if you try.