Chiefs (5)
I believe the answer is:
heads
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">chiefs</span>' is the definition.<br/ ><span class="explanation-format__explanation">('head' can be a synonym of 'chief')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for heads that I've seen before include "Coin-tossing call" , "a 50-50 chance" , "Leaders" , "School principals" , "Obverse result of coin-tossing" .)