Came down on unknown figure supporting injunction making dull observation (8)

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

'came down on unknown figure supporting injunction' is the wordplay.
'came down' becomes 'alit' (alight can mean to land).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'unknown figure' becomes 'y' (unknown value in algebra).
'supporting' says to put letters next to each other (in a down clue, some letters go below others).
'injunction' becomes 'ban' (I've seen this in another clue).
'alit' put next to 'y' is 'ality'.
'ality' put after 'ban' is 'BANALITY'.

'making' is the link.

Can you help me to learn more?