Heraldic creature (7)
I believe the answer is:
unicorn
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">heraldic creature</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for unicorn that I've seen before include "Fabulous creature" , "Fabulous one-horned animal" , "Animal rumoured" , "Imaginary creature with one horn" , "Mythical white equine" .)