There are avian vets on both sides of the issue. I prefer flighted partially because they get more exercise.
If you do decide to clip her wings, I would start with only a partial clip for balance reasons. Cockatiels sometimes end up doing this terrible "drop like a rock" thing if they are clipped too short. If you have never done it, have your vet show you how. You'll want to be able to do it yourself in any case; it's easy, I promise, and it's easy to find a guide online for a refresher. You do have to have the same vigilance that you would for a fully flighted bird because you really cannot assume that they cannot fly. One or two feathers growing in can make all of the difference. In addition, you also have to be extremely careful about doors, stepping on them, and anything hazardous that they could land on. They should still be able to sort of glide down to the floor, but they may not have a lot of control about where they land.