Setup:
1- Pick a target the distance your 7-iron goes on the range
2- Aim Alignment stick at target
Drill:
1- Take a 7-iron
2- Take a short backswing, and try to drag the handle of the club toward the ball
3- Maintain the angle between your lead forearm and the shaft of the club for as long as possible
4- Hold the lag all the way through impact and don’t release until after the ball is gone
5- Hit 15 balls like this. Flight should be low and you should see divots after the ball.
This is going to feel very weird and difficult at first, but it will teach you how to properly lag the club and you’ll start getting some nice compression on your shots.