Everyone knows that the key ingredient to a powerful clean is an explosive hip opening. If you forget to open your hips, the bar simply does not go up as high or as fast.
It occurs to me that not everyone knows that you have to close the hip again after you open it. What I mean is that if you open the hip and then catch the bar without closing the hip, you will be leaning back when you catch the barbell. This means the bar will come crashing down and most of the load will go right to your lower back. That is not the place we want the weight to go.
Open the hip, close the hip.