The full hanging leg raise involves hanging from a pull up bar and then lifting your legs all the way up so that your toes touch the bar. (unique-bodyweight-exercises.com)
In any case, if you want to perform it, you should be able to perform the hanging straight leg raise first. (fitnessandpower.com)
Try a side plank with leg raise: Get into a side plank with your legs stacked. (health.com)