State of REM leaving green room (6)
I believe the answer is:
oregon
'green room' is the definition.
The answer and definition can be both locations as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'state of rem' is the wordplay.
'state' becomes 'or'.
'of rem' becomes 'egon' (I am not sure about this - if you are sure you should believe this answer much more).
'or'+'egon'='OREGON'
'leaving' acts as a link.
Can you help me to learn more?
(Other definitions for oregon that I've seen before include "The American state is no goer, strangely" , "US west-coast state" , "American Pacific state" , "Part of the US" , "No gore spilled in this American state" .)