Spoken, not written (4)
I believe the answer is:
oral
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">spoken</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ >'<span class="explanation-format__original">not written</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(spoken rather than written)</span><br/ ><br/ ></span>
(Other definitions for oral that I've seen before include "See 18" , "Spoken - examination" , "Relating to speech" , "By word of mouth (4)" , "Kind of exam" .)