Concept, idea (6)
I believe the answer is:
notion
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">concept</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that notion is a type of concept)</span><br/ ><br/ >'<span class="explanation-format__original">idea</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that notion is a type of idea)</span><br/ ><br/ ></span>
(Other definitions for notion that I've seen before include "Idea or whim" , "desire" , "Idea, belief" , "Vague understanding" , "Idea, concept" .)