Totally fixable… although you may end up with a small dent still there, which can easily be filled.
Around new year someone pointed out that my Roadrat had a dent very similar to that on the top tube, in fact maybe a little worse. I’d not seen the dent before, but can only guess it happened when the bike fell against something, no idea when though.
Anyway, after a little searching I found that dents like that can be repaired using a tube rolling technique. Essentially you clamp two pieces of wood or metal, which are the exact diameter of the tube, around the tube using a vice. Then tighten the vice a little, rotating the frame in the clamps, then tighten some more, rotate, tighten, rotate, until everything is clamped up tight.
What it does is put pressure on the high points of the dent, pressing them in, which in turn forces the dent to pop back out again. Unforunately it doesn’t fully pop back out, but it comes most of the way. The other issue is that it takes a lot of paint off… which I ended up just cleaning up with some emory cloth and painting with some old car paint I had laying about… it’s a scrappy looking job, but it’s just my commuter. But nothing to stop you sanding the area down nicely, filling the remaining dent, cleaning it all up an then getting it repainted properly.
As for the clamping blocks, I made mine out of the hard wood I had kicking about, cut that in half and then bought a forstner bit for the drill to make a exact 28.6mm hole in the middle of the pair. You can also buy the blocks, which are pretty cheap over in the States, but seem to be like rocking horse poo over here unforunately.