Gruesome fiend (5)
I believe the answer is:
ghoul
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">gruesome fiend</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 ghoul that I've seen before include "Corpse-loving phantom" , "Spirit that robs graves and devours corpses" , "malevolent spirit" , "Evil presence" , "Morbid voyeur" .)