Your trusty fade has turned into a full-blown slice. The likely diagnosis? Through the hitting zone, you're either keeping your left arm bent (aka "chicken-winging" it), or failing to rotate your hands to square the clubface. You can fix either flaw by tossing a Frisbee. Here's how.
Hold a Frisbee in your left hand and assume your address position, letting your arms hang naturally. Grip the disc so that the underside faces your target.
"Swing" the Frisbee back while keeping your upper left arm tight against your chest. Let your left wrist flex back as you finish your backswing (photo below). The underside of the Frisbee should point toward the sky.
Quickly turn your left hip toward the target. You'll feel your left arm press even tighter against your chest, your signal to let the Frisbee loose. Whip your left arm and wrist toward the target. At the same time, rotate your left hand to the left, so that when the Frisbee flies, it soars right side up. Congrats! You've mastered the moves needed to both lag the clubhead on the way down and release through impact, for square, slice-free contact.