Crested lizard (6)
I believe the answer is:
iguana
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">crested lizard</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 iguana that I've seen before include "Tropical tree-lizard" , "Arboreal lizard of S America" , "Lizard Darwin found in the Galapagos" , "Arboreal lizard with a spiny crest" , "Herbivore" .)