First let’s concentrate on the club face at impact. Most hooks whether subtle or severe are caused by a closed club face. The reason is most likely due to premature wrist rotation. Your bottom thumb turns over too soon often before the club face makes contact with the ball/ground.
The first step to curing a hook is to make sure your hands and wrists are in the correct position at impact with ball/ground. You absolutely must be sure your wrists are not turning over too soon. You can practice this by chipping. Use a high iron, try a 7 or 8 iron. Start by taking your normal chipping swing/motion. If your ball is hooking, you’re most likely turning your writsts over.