I agree with "fixing your swing."
Why you slice any club be it driver, fairway wood or iron here is what happens. When you start your backswing you move your club and shoulders into the top of your swing and the weight transfers to your right side / foot. Now the brain says “to get back to impact you have to move your shoulders and club back in the same sequence as going back”. For every action sequence, there is a counter action sequence.
So if you follow what your brain senses, you will hit a slice, because you will come back to impact from an over the top or out to in move. If you want to hit the ball straight you have to
counteract
the backswing move on the downswing. To accomplish this, you have to move the weight to the left side / foot before you start the downswing, just the opposite sequence of the backswing. A tip, courtesy of Tommy Armour Sr., that I found helpful in accomplishing the transfer of weight is to raise your left heel about a ½ inch on the backswing. The first move in the downswing then is to
replant the left heel
. This move automatically shifts the weight and drops the hands and club into the slot……….try this in slow motion without a club a number of times until you understand the dynamics of this slice killing move………