Uncapped elixir, declared as the drink (5)

I believe the answer is:

ocean

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'the drink' is the definition.
('the drink' is an informal term for the sea)

I don't understand the rest of the clue.

(Other definitions for ocean that I've seen before include "Large amount of water and" , "Vast quantity of liquid" , "Indian perhaps" , "Huge body of water" , "Main" .)

I've seen this clue in the Sydney Morning Herald.

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