Jekyll's alter ego (4)
I believe the answer is:
hyde
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">jekyll's alter ego</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 hyde that I've seen before include "... the latter side of [EVIL] nature" , "Green space in London" , "Manchester town, London park" , "and 21 Across: Green area in London" , "Jekyll's alter ego" .)