Devil-worshipper (8)
I believe the answer is:
satanist
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">devil-worshipper</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 satanist that I've seen before include "Saint sat with devil worshipper" , "One who worships the devil" , "diabolical fellow" , "Devil devotee" , "Devil-worshipper" .)