Loose rocks over elevated cave shown (8)
I believe the answer is:
screened
'shown' is the definition.
(screen can mean to show a film)
'loose rocks over elevated cave' is the wordplay.
'loose rocks' becomes 'scree' (scree is a mass of loose rocks on a mountain).
'over' says to put letters next to each other.
'elevated' says the letters should be written backwards (in a down clue, letters go up).
'cave' becomes 'den' (I've seen this in another clue).
'den' backwards is 'ned'.
'scree'+'ned'='SCREENED'
(Other definitions for screened that I've seen before include "Shown in a cinema" , "shown on TV" , "Showed a movie" , "Involved in selection process" , "broadcast" .)