Piece of her coal broke (7)
I believe the answer is:
chorale
'piece' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'her coal broke' is the wordplay.
'broke' indicates anagramming the letters.
'her'+'coal'='hercoal'
'hercoal' with letters rearranged gives 'CHORALE'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for chorale that I've seen before include "Composition" , "Harmonised hymn tune" , "Lutheran hymn-tune" , "Simple hymn tune" , "Stately hymn tune" .)