An exercise designed for improving lower body strength, stamina and balance, the one-legged deadlift is a good choice of bodyweight exercise.
If you're finding the one-leg deadlift too difficult you can use your non-supporting leg to lightly touch the floor behind you for additional support.
If the exercise is well beyond your capabilities you should first try mastering the standard bodyweight deadlift before progressing on to the single-leg version.
When you've mastered the one-legged deadlift you can introduce more weight to add intensity to the exercise and continue to challenge the body.
Weighted vests are a good solution to control additional weight or you can simply hold dumbbells or kettlebells to help increase resistance and seriously challenge your lower body.