Beatty film (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">beatty film</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for reds that I've seen before include "Left-wingers" , "Colourful communists" , "Scarlet and crimson, say" , "Scarlet communists" , "First snooker balls to be potted" .)