ПОЗВОНОЧНИК _|_ SPINE / POZVONOCHNIK [pəzvɐˈnot͡ɕnʲɪk]   

Hint with alternative definition it is a spine-chief or boss as a base for posture & poise with a chain of bones «on a fine pause» (it mostly stays calm while hands, head & legs are moving)

Hint with transformations: поз-вон > боз-бон > boss-bone + очник (one chain)

Russian pro-tip: будто много колокольчиков в ряд = по + звон

Mental visualization: П (belt or bedrock) + ОЗВОНО (spinal bones) + ЧНИК (ribs) = spine