The easy answer...
Look out the front window!!!
Of course staying keeping the airspeed right and keeping in balance is the key to not spinning. But that's true of any stage of flight.
So what is it that makes the spin more likely to happen at this stage, apart from maybe being a little slower than during the cruise?
It's pilots who are trying to look at the runway during the turn - and therefore not watching the attitude. You will not notice that your speed is wrong nor that you are out of balance if your eyes are not on the horizon!
The issue is that you, naturually, want to see where you are turning towards. But in turning your head to look at the runway, you are looking away from the horizon, and therefore not aware of any changes in attitude or airspeed.
The problem is worse, IMHO, in a high-wing aircraft, because the view of the runway is obscured in the turn, meaning that you probably have to shift around in your seat to see the runway - and this will naturally involve you involuntarilly moving the controls.
Incidentally, I see my students loosing airspeed (in the high-wing Cessnas that I teach in) far more on the downwind-base turn than on the base-final turn. The reason, 99% of the time, is that they are trying to look at the runway to work out when to roll out of the turn. When turning final, the runway is at least ahead of you at the end of the turn, so you don't have to strain to see it. But when turning onto base in a high-wing aircraft you must have some other method of working out when to roll out of the turn. The answer? Before you roll into the turn, pick a feature just in front of the left (or right, for a right-hand circuit) wing. Then start the turn, keep looking ahead, and stop the turn when your pre-selected feature appears in the windscreen. As you roll out of the turn, you can then look at the runway and make adjustments. This will enable you to be aware of your attitude, and therefore your airspeed, right the way through the turn.
To answer the second part of the question, if you ignore all the advice here and get it wrong..... I don't believe there is any way of recovering from a spin at that level in most aircraft before hitting the ground. But the training you get in spin recognition and avoidance as part of your PPL should train you to lower the nose, apply full power, level the wings and climb away well before the situation develops into a full spin. That is precisely why, for the PPL skills test, you are required to recover from this situation at the first sign of the stall, namely either the light buffet or the stall warner, whichever occurs first.
FFF
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