Prehistoric reptile (8)
I believe the answer is:
dinosaur
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">prehistoric reptile</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 dinosaur that I've seen before include "relic" , "Extinct beast" , "type unable to adapt" , "Prehistoric monster found on Darius" , "One as T. Rex, triceratops" .)