The clubhead should be descending at impact with the exception of the driver and the putter. What is meant by the descending angle of approach?
Many players do not truly understand this term and its meaning. Some think this means hitting down on the ball. Not so! Trying to get the ball airborne is the move that disturbs this clubhead path. The loft of the clubface is sufficient to lift the ball. Attempting to lift the ball tends to open the clubface, which will slice the ball and lose distance as well.
To have a good angle, the left leg passes the ball first, hands second and clubhead last. This motion automatically moves the clubhead in the descending angle of approach. Having the clubhead passing the hands prior to impact creates an ascending angle of approach. Most of the time with this action the clubhead will hit the ground behind the ball (chili dipping) or the swing bottoms out early and the ball is struck on the upswing, topping it.
To check your clubhead angle practice the 'hit and hold' drill. This will give you immediate feedback in determining whether the clubface is preceding the hands at impact. Hit a few balls and hold, not allowing your hands to go past waist high on the follow-through. If the left wrist or hand is bent forward, this indicates the clubhead was ascending rather than descending at impact.
Final note: You cannot cheat this drill, as it will clearly show you where you are in regards to your angle of approach on your golf swings.