[That look. How he has missed that look, that undying trust resting in her gaze, even after just one day without her. He wants to tell her that everything will be okay, since that's exactly what this look demands, but ...]

I'm sorry, Clara, I really am. We are cut off from the Time Vortex, completely without a connection to it. I'm trying - every day - to fix it but ...

[He doesn't have to say anymore, since she'll know what that means. That it's not something he can do, that no matter how many problems he's solved, how many apparent miracles he's made happen, this is not one of them.]

This is a pocket universe, effectively. Like the one we recued Hila Tracorien from. Only this time we don't have four seconds to escape and it is not collapsing in on us. It's stable which is both weird and good for us.