Outside of an egg (5)
I believe the answer is:
shell
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">outside of an egg</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for shell that I've seen before include "Empty case" , "Conch, perhaps" , "Mortar missile" , "Hard casing; a racing boat" , "Carapace; bombard" .)