Typewriter roller (6)
I believe the answer is:
platen
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">typewriter roller</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 platen that I've seen before include "One working in the press" , "Roller against which typewriter keys strike - ten lap (anag)" .)