Note a calculation about songs (5)
I believe the answer is:
music
'note' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'a calculation about songs' is the wordplay.
'a calculation' becomes 'sum' (I have seen 'Arithmetic calculation ' mean 'sum' so perhaps 'calculation' could also mean 'sum').
'about' is a reversal indicator.
'songs' becomes 'ic' (I can't explain this - if you can you should give a lot more credence to this answer).
'sum' backwards is 'mus'.
'mus'+'ic'='MUSIC'
Can you help me to learn more?
(Other definitions for music that I've seen before include "Organised notes (that must sometimes be faced)" , "Country, say" , "'Fled is that ---: do I wake or sleep?' (Keats)" , "Pleasant sound (to one's ears)" , "'If ... be the food of love, play on'(Twelfth Night)" .)