This is a really simple drill that might help you cure your slice.
Everyone wants an easy cure for this shot, as things can get complicated very easily. The reason people slice the ball, or the most common reason people slice the ball, is because their club is attacking the ball too much from out-to-in.
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So, for a right-handed player, they are swinging too much to the left of the ball to target line, with the clubface open to that path. That’s what causes a slice.

The drill
This drill is easy. Close the clubface very slightly, take your normal golf grip, then address the ball so that your clubface points very slightly left of target. This will encourage you to swing more from the inside.
Because you’ve made this change - and because it looks odd at address - you won’t want to swing left with the clubface aiming left. I use it a lot during my lessons and it’s a really easy drill to try on the range.
You need to swing from the inside so, by setting up with the clubface pointing left before you start your swing, it encourages you to not swing left. Looking down, you won’t want to hit it left, so you’ll instinctively swing from the inside.

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Try this
Before you do that drill, it’s a good idea to hover the club above the ball and make some baseball style swings, because that’s the type of feeling you want to try and recreate doing that drill.