Fell backwards in lounge, perhaps (4)
I believe the answer is:
room
'lounge perhaps' is the definition.
(lounge is a kind of room)
'fell backwards' is the wordplay.
'fell' becomes 'moor' (I've seen this before).
'backwards' says the letters should be written backwards.
'moor' written backwards gives 'ROOM'.
'in' is the link.
(Other definitions for room that I've seen before include "Space; part of building" , "See 17" , "basic accommodation" , "Opportunity, scope" , "Space; chamber" .)