What does your takeaway look like? I’ve seen this a lot with golfers who slice. It goes from here to here, which is not good.
A quick and easy way to ensure you’re taking the club back on the correct plane is this: setup to your shot…tuck your grip into your belly and start your backswing.
What you’ll instantly notice and feel is that you can’t start your backswing with just your hands, or just your arms…you have to make one connected movement.
A tool like the Liveview makes this even easier where you can see where the club is during the back swing in relation to it’s plane.