Night demon (7)
I believe the answer is:
incubus
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">night demon</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 incubus that I've seen before include "Demon bringing nightmares" , "Burdensome person or evil spirit visiting sleeper" , "Oppressive burden" , "Evil spirit visiting a sleeping person" , "Male demon - nightmare - obsession" .)