Fell over in snug, perhaps (4)
I believe the answer is:
room
'snug perhaps' is the definition.
(I know that cubby is a type of room)
'fell over' is the wordplay.
'fell' becomes 'moor' (both can mean an expanse of wild land).
'over' says the letters should be written in reverse.
'moor' back-to-front is 'ROOM'.
'in' is the link.
(Other definitions for room that I've seen before include "Enclosed space in a building" , "Latitude" , "Adequate space" , "Space; part of building" , "Space; chamber" .)