My lifestyle these days don't allow me to train in a club, but I do try to recall drills from college kickboxing class. I recall 2 ways of doing the shuffle roundhouse. I'm trying to choose the right one to fit into a combination.
Assume an orthodox stance. After a jab and a cross, the front left leg gets shuffled to be come the back leg (for an instant) so that it can throw a powerful roundhouse. The two ways that I recall shuffling the left leg back are:
(1) Slide the left foot back to approximately the level of the right foot, or maybe a bit behind it, then step forward with the right foot. The left foot is now well behind, and immediately throws a roundhouse. I guess the stepping forward of the right leg generates power.
(2) Just hop into a southpaw stance and bounce the rear left leg into a roundhouse.
Ideally, one would practice many different variations of a shuffle roundhouse, but if time is lacking, which one would be better to favour in drills?