Screen third attempts (7)
I believe the answer is:
reredos
'screen' is the definition.
(a reredos is an ornamental screen)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for reredos that I've seen before include "Wall decoration behind altar" , "Ornamental screen behind a church altar" , "Church feature" , "Red rose could show a screen behind the altar" , "Fireback" .)