Governs (5)
I believe the answer is:
rules
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">governs</span>' is the definition.<br/ ><span class="explanation-format__explanation">('rule' can be a synonym of 'govern')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for rules that I've seen before include "Is king" , "Reigns" , "Laws; draws lines" , "is supreme, OK?" , "Conventions" .)