Not mapped (9)
I believe the answer is:
uncharted
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not mapped</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for uncharted that I've seen before include "Not mapped for navigation" , "Of regions not yet surveyed" .)