Rules of language (7)
I believe the answer is:
grammar
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rules of language</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for grammar that I've seen before include "Branch of language study" , "Syntax etc" , "Basic rules of language" , "Branch of linguistics that deals with syntax" , "Study of word and sentences" .)