You can find this exercise on page 22 of the book Synergistic Golf.
Exercise Type: YOGA-STRETCH
Exercise Category: FLEXIBILITY, HIPS, LEGS - FEET, LOW BACK
Lie on floor with arms straight out to sides in a letter T position. Lift left leg straight up to sky and cross over body so that left foot almost touches right hand. Can you keep both shoulder blades and hands on the floor? Hold for 10 seconds then alternated legs 5 times.