Chest bone (3)
I believe the answer is:
rib
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">chest bone</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for rib that I've seen before include "Thin bone" , "Chest bone, may be floating" , "Guy" , "Poke fun at the bone" , "One of the 12 pairs in the body" .)