Abstruse; indistinct (7)
I believe the answer is:
obscure
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">abstruse</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">indistinct</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for obscure that I've seen before include "Dim, indistinct or not well known" , "Unsung" , "Not clear, indistinct" , "Little known - dark" , "Blot out" .)