Label paintings put up on loan finally out of Denmark (9)
I believe the answer is:
trademark
'loan finally out of denmark' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe there's an association between them I don't understand?
'label paintings put up on' is the wordplay.
'label' becomes 'demark' (I can't explain this - if you can you should believe this answer much more).
'paintings' becomes 'art' (I've seen this before).
'put up' says the letters should be written backwards.
'on' is a charade indicator (letters next to each other).
'art' back-to-front is 'tra'.
'demark' after 'tra' is 'TRADEMARK'.
Can you help me to learn more?
(Other definitions for trademark that I've seen before include "distinctive characteristic" , "Registered sign of a manufacturer" , "typical" , "Proprietary name" , "Distinctive sign" .)