Remarks on jacket having a smear on top of buttonhole (5)
I believe the answer is:
blurb
'remarks on jacket' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'a smear on top of buttonhole' is the wordplay.
'a smear' becomes 'blur' (I've seen this in another clue).
'on top of' indicates taking the first letters.
The first letter of 'buttonhole' is 'b'.
'blur'+'b'='BLURB'
'having' acts as a link.
Can you help me to learn more?
(Other definitions for blurb that I've seen before include "Promotional text for a book" , "Promotional book description" , "Publisher's book description" , "giving brief description of it" , "Commendations on book jacket" .)