There is one "drill" I can suggest if Greg's RH drill or the impact bag doesn't do it for you. It's not really a drill in the true sense, it's more of an execution and a feeling:
Try to get the feeling that on the downswing when the club reaches parallel to the ground at around hip height, the armsand hands create a 90* (or close to) with the club. The arms, hand and club should form an L shape.
Then from there hit through impact with as much energy as you can. The club moves a great deal (from hip height into and through impact) while the rest of the L move very little becuase your arms and hands are close in being in line with the ball anyway.
It's the age-old "late hit" routine that seems to have fallen out of favour these days, which is a pity because the "late hit" is still an important part of the modern golf swing but it blends into other impact alignment drills...
Give it a go, it may help. If not, try it again.
