I actually don't think it's that at all. CyberDoctor wondered why the Doctor thought about Clara so much. The obvious conclusion is that he was attracted to her, but that's incorrect. Or, at least not the main reason. It's because she's the impossible girl.
I thought it was great that Clara knew that wasn't the Doctor because she knows he doesn't see her that way. Although, it was lame how the CyberDoctor was still able to destroy the detonator which she conveniently brought to him.
I'm not talking about that moment, or the time with the Doctor and CyberDoctor arguing in his head. I know that was fake. I'm talking about the last moment of the episode before the teaser. I'm not usually a shipper. And I don't know if I want these two to get together yet, but how do you interpret the last line?
"Impossible girl! A mystery wrapped in an enigma squeezed into a skirt just a little too....tight...." (and then his face, as he slips off into a reverie for a few seconds, smiles, then snaps out of it, looking appalled with himself) "What are you?!"
He finds her attractive and he doesn't want to. It's funny. I don't see how else one can interpret that last scene.