Introvert (5)
I believe the answer is:
loner
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">introvert</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for loner that I've seen before include "One shunning company" , "Unsociable person" , "One not desiring companionship" , "One who avoids company" , "Solitary individual, prefers own company" .)