I think clavicles are way too luscious, therefore they should be banned from this PG-13 site. We should protect the children from being exposed to sexually implicit content.
Any figure whose genitals, pubic hair, buttocks, or (if female) nipples, areolas or clavicles are exposed, partially or totally; or are not exposed, but it's clear that this is only because of the angle of the shot or incidental intervening objects (e.g., hands, hair, bits of cloth).
Just think of it...
A collarbone today, naked areolas tomorrow?