Old Harry (5)
I believe the answer is:
satan
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">old harry</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for satan that I've seen before include "Old Nick, Lucifer or Beelzebub" , "Prince of Darkness" , "Diabolical figure" , "Fiend" , "Apollyon" .)