Sounds like a pretty poor clear coat is mere tape pulled some off the color. If you spray clear over this area there will be a ring of the new clear misting out and the old clear remaining. This could result in a hazy or dull look. Also there's no guaranty that the new clear will change the color to end up looking exactly the same as that which is still covered by the old clear. Additionally there's likely to be a thickness change still present after. lastly I would be concerned about the old clear's ability to stay put, given that it lifted off in the first place.

But we don't know yet what kind of color and clear was used to begin with. So any speculation at this point is just that. Good luck and maybe start looking for a different painter for your next frame. Andy.