Was it the first or last shot on the roll?

You could always try and snip that frame off in the darkroom and process it separately. Use a previously developed film as a guide to make a cardboard gauge to let you know where to cut.

Obviously you will ruin one frame because you'll never manage to find the edges of the frame accurately enough (better to sacrifice the next frame and aim for the centre of it) - but maybe better to waste 1 frame than 11?

Even if it is in the middle, maybe better to waste 2 than 11?