by no means am I a master bowyer, never had to fix one with that there problem. as an old world cabinet and furniture maker i may lend a tip.
looks like the separation is not up to the working portion of the limb, maybe a touch right at the end of the fade, so;
1st- put a clamp at both ends of the separation. keep them on until step 10.
2nd- clean out with a thin file, like paper thin, don't get too crazy with it.
3rd- blow out all the debris and dust with air hose. all.
4th- get a few more clamps and clamp the separation together(dry run, NO GLUE!) to see if there are any gaps at all. make a tapered block to fit the riser belly for even clamping pressure.
5th- repeat step 2-4 a few times. seriously.
6th- get glue(smooth-on, epoxy, etc.) and supplies ready, take deep breath.
7th- get your glue in there any way you can, eg. pop-cycle sticks, toothpicks, anything to get the glue in there and full coverage.
8th- put on your clamps, but don't turn all hulk like and cause a starved line. =bad.
9th- put in hot box for a few hours no hotter than say 100f, or use a couple heat lamps a foot or so away from the area.
10th- once glue is dry, remove clamps and clean it up and inspect, diligently, to see how you did. if not good, put on the wall, have a beer, if all good, sit back have a beer and praise yourself.
11th- finish sand the area and apply new finish. have another beer.
if you tape up the surrounding areas before gluing up, it helps beyond measure with cleaning up and sanding.
good luck, take pics of the process(whatever route you take) and post them up for others to find if they run into the same problem.