Is not open or shut? (6)
I believe the answer is:
closed
This clue is a double definition.
'is not open' is the first definition.
('closed' is the opposite to 'open')
'shut?' is the second definition.
(I know that closed can be written as closed)
'or' acts as a link.
(Other definitions for closed that I've seen before include "Shut" , "See 1" , "Blocked off" , "Not longer open" , "restricted" .)