Dead as a dodo! (7)
I believe the answer is:
extinct
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">dead as a dodo</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 extinct that I've seen before include "No longer in existence" , "No longer living, like dinosaur" , "Having died out, perished" , "No longer erupting" , "gone forever" .)