Upset pain internalised dogma (9)

'dogma' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe you can see an association between them that I can't see?

'upset pain internalised' is the wordplay.
I cannot really understand how this works, but
'pain' could be 'aching' (aching is a kind of pain) and 'aching' is located in the answer.
'upset' could be 'tes' ('set' written backwards or 'up') and 'tes' is located in the leftover letters.
No letters remain.
This explanation may well be incorrect...

Can you help me to learn more?