Fellow at Oslo ruined cover page (8)
I believe the answer is:
foolscap
'page' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'fellow at oslo ruined cover' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'at' says to put letters next to each other.
'ruined' indicates an anagram.
'cover' becomes 'cap' (capping is a kind of covering).
'oslo' with letters rearranged gives 'ools'.
'f'+'ools'+'cap'='FOOLSCAP'
Can you help me to learn more?
(Other definitions for foolscap that I've seen before include "Cop's foal (anag)" , "One would not be wise to put this on" , "type of paper" , "Paper or book size (from its watermark)" , "something near A4" .)