King's fool ruined one less traditional air (4,4)
I believe the answer is:
folk song
'ruined one less traditional air' 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?
'king's fool' is the wordplay.
I cannot quite see how this works, but
'king's' could be 'ks' (abbreviation for king in chess) and 'ks' is present in the answer.
an anagram of 'fool' is 'folo' which is present in the left over letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for folk song that I've seen before include "Traditional ballad" , "eg 'The Lincolnshire Poacher'" .)