Theatrical friend in hotel, having forgotten new address (7)

I believe the answer is:

horatio

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'address' is the definition.
Both the answer and definition are singular nouns.
Maybe there's a link between them I don't understand?

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for horatio that I've seen before include "- Nelson, British admiral" , "Speaker of Good night, sweet prince (Hamlet)" , "Nelson's first name" , "Hamlet's friend: Hornblower's first name" , "Nelson or Hornblower?" .)

I've seen this clue in The Guardian.

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