Flat circular plate (4)
I believe the answer is:
disc
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">flat circular plate</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for disc that I've seen before include "Thin circular plate, as in CD" , "put on by jockey?" , "Sound recording" , "something moving in the spine" , "Thin flat circular object" .)