Crossword Genius

Bottle -- what could be in it? (6)

Ross

I believe the answer is:

spirit

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

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for spirit that I've seen before include "Liquor or spectre" , "verve" , "Jinn" , "Incorporeal supernatural being" , "Mood - ghost - alcohol" .)

I've seen this clue in The Telegraph.
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