Clara spends half this episode as a waxwork doll, then faints and falls into the Doctors arms. Its not her greatest moment of action or agency. Her response is to pick up a chair and violently hurl it into the inner workings of the crazy villainess's world-ending device. She doesnt for a moment defer to the Doctor, wait for a better moment, or give the sonic a chance to work: she just throws a chair at the machine and watches what happens. In a scene full of violent women where the Doctor just sort of jumps about trying to talk people down, Claras act was definitely the cleverest and the coolest.