Can ailerons control a broken cable on 1/3 flaps?

[JimC]

I don't agree that it would work at higher airspeeds but not lower. The dynamic pressure would change on both the flap and the aileron as you slowed - so the single deployed flap would be producing less of a rolling moment as you slowed.

I also don't agree that "control-issue" approaches are always flown at higher airspeeds. It depends on the issue. For example, if I have a broken elevator control cable and I'm using trim to adjust pitch, why would I come in at a higher airspeed?

As far as the original question? We have no way of knowing, but I share your same guess - yes, ailerons could counteract the roll, but you'll need a big dose of rudder to counteract the yaw as well. You might not even have enough rudder - certainly not enough for any crosswind.