Sect (4)
I believe the answer is:
cult
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sect</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for cult that I've seen before include "Popular cause, fashion" , "Strange religious group" , "Narrow or excessive devotion to person or religious system" , "they believe" , "Extremist religion" .)