Having the ability to choke down on a golf shot and reduce the distance and height it flies, and at the same time increasing the control and accuracy that you have, is a worthwhile skill to be able to practice. You will find that you have numerous causes to play that three quarters shot in a normal round of golf.
This shot will often be hit with a short or medium iron; therefore, if you practice with a nine iron, you may get the best results and be able to transfer the skill to other clubs at a later stage.
Take your normal nine iron setup and now go ahead and reduce the width of your stance by a few inches, grip down on the golf club by an inch, and position 20% extra body weight towards your front foot. This address position should now feel less powerful but more controlled.
During the backswing phase of the three quarters swing, focus on making a good shoulder turn but keep the hands and the arm relatively passive and directly in front of your chest. Don't allow too much body weight to sway towards your right foot, maintain a front footed bias.
During the downswing phase of your three quarter shot, turn nicely to your front foot and create a feeling of being more passive with your hands and arms, therefore not releasing the golf club with a fast rotational motion. Instead hold the club more in front of the body, pointing more towards the flag and not fully wrapped around your back like you may do in a full swing.
The resulting three quarter swing should produce a golf ball that flies roughly 3/4 of its normal desired distance. The benefit of this swing is it should produce consistency and accuracy under pressure when you need it the most. Once you have mastered the basic nine iron swing start to experiment with other clubs in your bag, you may be surprised at how consistent you can be with this new technique.