One hears (8)
I believe the answer is:
listener
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">one hears</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 listener that I've seen before include "One trying to hear" , "One pays attention in order to hear" , "Tough crossword" , "One attending" , "Radio adherent" .)