Festive wit one got from a poster (9,4)
I believe the answer is:
christmas card
'festive wit' 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?
'one got from a poster' is the wordplay.
I cannot really see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found within the answer.
'a' is found in the answer.
'poster' could be 'card' (synonyms) and 'card' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for christmas card that I've seen before include "Seasonal greeting" , "It's too late to post it now" , "Seasonal missive" , "seasonal message - with 29a" .)