Rule, regulation (3)
I believe the answer is:
law
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">rule</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that law is a type of rule)</span><br/ ><br/ >'<span class="explanation-format__original">regulation</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for law that I've seen before include "Rule of conduct" , "Legislation" , "Commandment" , "Set of rules laid down by authority" , "Collection of rules imposed by authority" .)