Early bird? (3)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">early bird?</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for egg that I've seen before include "Reproductive unit" , "Organism protected by shell" , "Poached item?" , "start in life" , "Thin-shelled reproductive body" .)