Farewell letters read aloud (3,3)

I believe the answer is:

see you

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'farewell' is the definition.
(I know that farewell can be written as see you)

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for see you that I've seen before include "Casual and informal goodbye" , "Later we'll meet" , "For so long" , "Cheers" , "Informal kind of au revoir - with visual intent" .)

I've seen this clue in The Independent.

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