Gentleman's address? (3)

I believe the answer is:

sir

I believe this is a double definition.

'gentleman's' is the first definition.
(a man may be addressed as sir)

'address?' is the second definition.
(I have seen 'formal address' mean 'sir' so perhaps 'address' could also mean 'sir')

(Other definitions for sir that I've seen before include "Formal term of address" , "Title given to baronet" , "Baronet's title" , "Form of address for a knight" , "Feted fellow" .)

I've seen this clue in The Sun, The Telegraph, The Times, the Family Time, the King Feature Syndicate and the Universal.

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