Axiom or maxim (5)
I believe the answer is:
adage
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">axiom</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">maxim</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for adage that I've seen before include "Short statement expressing a general truth" , "Old saying, maxim" , "Well-remembered proverb or saying" , "Dictum" , "Saying, saw" .)