Fabulous creature (7)
I believe the answer is:
unicorn
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fabulous creature</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 unicorn that I've seen before include "Fabulous beast like horned horse" , "fabulous thing to behold" , "Fabulous one-horned animal" , "Imaginary, horned horse-like creature" , "Team of three" .)