One of the key components of the club lifting up and away from the body in the backswing is that the arms become disconnected from the technique. And as the arms become disconnected from the technique, it is at this point that you can really focus on and work on to try and help improve the overall swing and the overall rotation, going back end through ball.
Now fortunately there are number of very simple drills that you can use. And this is probably one of the easiest. If you have a spare glove or spare towel or you have it shirt which is a slight, a little bit bagging, you can pull material around slightly, all you need to do is grab material from underneath your left arm, fold it outwards and pinch it in underneath the joint here. Now what this will do, you will be able to feel that slight amount of material within between your arm and the side of your chest. If your arm comes away from your body that material will come lose, and you will feel it fall out so if you scratch that material out and hold it underneath your arm. Now all you need to be doing now is on the backswing, get the feeling that that material is being held inwards and you are turning back and you are turning through. If you can manage to keep that position exactly where it is then the arms will not become disconnected from the body, they will stay nice and connected with the turn and you should be able to hit more consistent golf shots. With it being pinched into begin with is quite an awkward feeling. So I wouldn’t start with full swings, only semi one, half way back half way through, to keep that connected back, keep that connected through and just focus more on turning the body back and through the technique.
You can also do the opposite, you can put it underneath the right elbow although this is more a case of if the elbow is coming out and flying away, but you can use the right elbow if underneath the left armpit feels a little bit uncomfortable. Do give that one a go because that will really nail down where the problem is, as far as those arms and the club lifting up and away from the body.