Lunatic (6)
I believe the answer is:
maniac
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">lunatic</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that lunatic can be written as maniac)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for maniac that I've seen before include "Mad (keen) type" , "Obsessive enthusiast" , "Psycho" , "Can aim (anag.)" , "Extremely wild person" .)