you're probably taking the club back too deep too quickly or standing too close to the ball. You're almost definately moving your head too much.

Go back to basics. Take a 9 iron and work on your fundamentals. Get your grip right, set-up and alignment correct, make sure you're balanced and then work on making your takeaway correctly.

Feel like you push your hands back low and wide. This will establish a good arc to the swing. Just make simple 1/2 and 3/4 swings focusing on swinging nicely through the ball. your goal is to swing in balance.

It's so essential that you get the fundamentals correct.