State of REM leaving green room (6)
I believe the answer is:
Here is my best explanation:
'green room' is the definition.
The answer and definition can be both locations as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'state of rem' is the subsidiary indication.
'state' becomes 'or'.
'of rem' becomes 'egon' (I am not sure about this - if you are sure you should believe this answer much more).
'leaving' is the link.
(Other definitions for oregon that I've seen before include "The "Beaver State"", "Pacific coast US state", "W. coast US state", "State of north-west US", "US region", "No gore seen in this American state", "Gooner (anag) - US state", "area of America", "America's Beaver State" and "US north-western coastal state".)