Hide the mass of loose mountainside stones before the north (6)
I believe the answer is:
screen
'hide the mass' is the definition.
'screen' can be an answer for 'hide' (I've seen this before). I am not sure about the 'the mass' bit.
'loose mountainside stones before the north' is the wordplay.
'loose mountainside stones' becomes 'scree' (I've seen this before).
'before' says to put letters next to each other.
'the north' becomes 'N' (abbreviation).
'scree'+'n'='SCREEN'
'of' is the link.
Can you help me to learn more?
(Other definitions for screen that I've seen before include "Partition; monitor" , "Conceal or sift" , "Guard" , "Divider to select for suitability." , "Room partition; vet" .)