Work some very fine powdery sawdust into the gap making it a bit proud of the top. put a few drops of CA glue (liquid, not gel) on the sawdust so that it soaks through. If that brings the sawdust below the top sprinkle a bit more on and add another drop of glue. It won't harden instantly. let it cure for 24 hours then sand it off. If you need some sawdust give me a shout, I've got a bunch.
Another option would be to cut some strips of brown paper (like what they use as packing material) and slide them into the gap using enough to make a pretty tight fit. Make the paper strips large enough so that they're proud of the handle by 1/4" or so. Put some liquid CA glue on the edges of the paper so that it runs down the paper into the gap. You don't need a lot, it soaks through pretty quickly and this method avoids a lot of overrun cleanup. Let cure 24hrs and sand.
Eric