Sauce bottle (5)

I believe the answer is:

nerve

I believe this is a double definition.

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

'bottle' is the second definition.
(both can mean courage)

(Other definitions for nerve that I've seen before include "Bodily fibre that communicates sensations" , "Spunk" , "Grit" , "Impulse transmitter - bottle" , "Fibre that carries instructions to the brain" .)

I've seen this clue in The Telegraph, The Guardian, The Times, The Sun and The Sunday Times.

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