Hello,
i´ve made a human model with the mirror-modifier and do-clipping activated. Unfortunately now both feet hang together at one vertex. How can i divide the feet?

deactivate do-clipping, move that feet, and activate the do-clipping again

OK, thank you, but unfortunately i´ve applied the modifier already. Is there any possibility to change this now or do i have to use a back-up?

well, your model is symmetrical so you could just delete one half, fix your problem and then aplly mirror. Or just select that vertex and press V button, that will split it to two vertexes.

Thank you very much. That was just what i wanted to know