A common problem with the clean is athletes letting the bar crash onto them in the turnover. In other words, the bar falls into the rack position rather than the bar and shoulders connecting smoothly. This creates excessive downward force on the lifter, encouraging collapsing of the trunk, a loss of position, poor timing in the transition out of the squat, and an unnecessarily difficult recovery.
Lifters who make this mistake are usually trying to rush into as deep of a squat as quickly as possible, moving down indiscriminately instead of actually pulling under the bar and remaining connected to it. The goal is to bring the bar and shoulders together smoothly so the lifter can absorb the weight and maintain position and rigidity—in other words, to meet the bar at whatever height it’s been pulled to.
Simply put, meet the bar with your shoulders in the turnover at whatever height you’ve pulled it to.