Impossible fancy (7)
I believe the answer is:
chimera
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">impossible fancy</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for chimera that I've seen before include "fake image" , "Idle fancy" , "Each rim (anag) - foolish fancy" , "wild dream" , "figment of the imagination" .)