Very effective composition, marred by details. If that's a womans foot, have her shave and do the nailpolish before reshot. Great treatment of the challengel.
I love the idea behind this, and the setup itself is not bad. From a purely aesthetic POV however, to make this as racy as possible, I think the lady's foot could have used a good pedicure and possibly some lotion, and maybe even a shave on the lower leg...those little details might be the difference in a point or two on the score. Technically, the image is OK but the shadow is a bit distracting.
Interesting idea, I think some people even enjoy this kind of 'bondage' (is that what it's called?). Your lighting disturbs me. The most important elements are in the shadows. The light source should be in the opposite direction. 4.