Old prince shortly drinking a bottle of medicine (5)

I believe the answer is:

phial

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'bottle of medicine' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for phial that I've seen before include "Small bottle for potions etc" , "little bottle" , "Ampoule" , "Small glass bottle for perfume or medicine" , "Small flask" .)

I've seen this clue in The Guardian.

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