Small stones in bottle? (4)

I believe the answer is:

grit

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

I can't explain the remainder of the clue.

(Other definitions for grit that I've seen before include "Toughness" , "Kind of courage or dirt" , "Jock's enormous" , "Small particles of stone or sand" , "Courage, determination" .)

I've seen this clue in The Times.

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