Flat carrier (4)
I believe the answer is:
tray
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">flat carrier</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 tray that I've seen before include "Flat surface for carrying things" , "Board for carrying items" , "Bearer" , "Domestic carrier" , "Kitchen carrier" .)