Relaxed, unofficial (8)
I believe the answer is:
informal
This clue is a double definition.
'relaxed' is the first definition.
(informal can mean relaxed or casual)
'unofficial' is the second definition.
(similar in meaning)
(Other definitions for informal that I've seen before include "Casual and unceremonious" , "Casual, not official" , "Casual, free and easy" , "Cosy -- loose" , "If normal, be casual and without ceremony" .)