Poetry that’s deadpan? Very old language (5,5)
I believe the answer is:
blank verse
'poetry' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'deadpan? very old language' is the wordplay.
'deadpan?' becomes 'blank' (I am not sure about this - if you are sure you should believe this answer much more).
'very' becomes 'v' (common abbreviation).
'old language' becomes 'erse' (old-fashioned term for Gaelic).
'blank'+'v'+'erse'='BLANK VERSE'
'that's' is the link.
Can you help me to learn more?
(Another definition for blank verse that I've seen is " Rhymeless poetry".)