Leaders (6)
I believe the answer is:
chiefs
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">leaders</span>' is the definition.<br/ ><span class="explanation-format__explanation">(chief is a kind of leader)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for chiefs that I've seen before include "Bosses, gaffers" , "Bosses, heads" , "Leaders, bigwigs" , "Leaders, bosses" , "Heads top dogs" .)