The ones in the frame? (4)
I believe the answer is:
reds
'the ones' is the definition.
Although both the answer and definition are plural nouns, I cannot see how one could define the other.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for reds that I've seen before include "Scarlet communists" , "Left-wingers" , "Tidies up" , "Scarlet and crimson, say" , "Colours for communists" .)