The proper hip motion isn't 'around' as much as it is diagonal. At the top of the backswing, you want to feel like you 'sit on your right cheek', which lets you fire your right side to the inside back corner. When folks try to 'turn' the hips to start the backswing or downswing, the club gets over plane instantly (rolls in and over going back, out and over going down)
The 'fire your right side' folks, like ballard, neglected to share the critical part - that everything comes from 'inside' to on, to 'inside', including the hip motion. Think 45,90,180 degree angles.
Think of drawing your right hip 'back', instead of 'turning' the left hip 'around' - fire it at the inside back corner. Most folks 'spin', and unless you are a hooker with lots of lag, you are over plane, with a seriously open club, and are forced to save the shot with the shoulders - instant slice
It ALL comes back to understanding the whip, understanding LAG and moving your body in a way that 'supports' the swinging 'whip' motion of the club, from the ground up.
Probably the best way to ensure you know the feeling of a firm left side (i.e. not too 'around' - which it seems you do) - is to do left hand only swings, as if you were throwing a frisbee with the left hand, and try to hit hooks out to right field that sweep back to center. Use a slightly strong lead hand grip for this drill, and focus on the left thumb, and its rotation ON plane. Once you understand the feel, I think you will understand the 'around' vs. diagonal hip motion.
You will also understand how easy it is for the right arm to extend through the shot, a new feeling for most because they have been coming 'over' for so long.