Crossword Genius

Two characters in elevated correspondence? (3,6)

Ross

I believe the answer is:

air letter

I'm a little stuck... Click here to teach me more about this clue!

'elevated correspondence?' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

'two characters' is the wordplay.
'two characters' can mean two replacements for 'character'.
'character' becomes 'air' (air can mean a character or mood).
'character' becomes 'letter' (letter is a kind of character).
'air'+'letter'='AIR LETTER'

'in' acts as a link.

Can you help me to learn more?

(Other definitions for air letter that I've seen before include "speedy delivery" , "Item of overseas mail" , "Item of overseas post" .)

I've seen this clue in The Independent.
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