You're going to have to overlay a second copy of the clip on a lower track, then use the Mask Designer to only allow only the hand in that clip to show. You can then drastically reduce the brightness and make any other saturation and contrast changes on that clip to get that section to more closely match the rest of the scene, which will show "behind" the masked clip.
You can use an existing mask shape or create one of your own. Either way you'll probably want to feather the edges to have the clips blend smoothly. There are many tutorials on using masks if you're not familiar with them.