Kept nice spot semi uncovered always for magnum opus (4,4)
I believe the answer is:
epic poem
'opus' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe you can see an association between them that I can't see?
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for epic poem that I've seen before include "Long verse" , "E.g. the Iliad, Paradise Lost" .)