Right; conventional (6)
I believe the answer is:
proper
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">right</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that right can be written as proper)</span><br/ ><br/ >'<span class="explanation-format__original">conventional</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for proper that I've seen before include "Correct in behaviour" , "Genuine; respectable" , "Refined" , "Genuine; suitable" , "part of Mass" .)