Hidden under lots of loose rocks is Edmund (8)
I believe the answer is:
screened
'hidden' is the definition.
'under lots of loose rocks is edmund' is the wordplay.
'under' is a charade indicator (letters next to each other).
'lots of loose rocks' becomes 'scree'.
'is edmund' becomes 'ned' (I've seen this in other clues).
'scree'+'ned' is 'SCREENED'.
(Other definitions for screened that I've seen before include "made available to view" , "Shown in a cinema" , "Not viewable" , "broadcast" , "put on TV" .)