Standard liquid for soup (5)

I believe the answer is:

stock

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This clue might be a double definition.

'standard' is the first definition.
(synonyms)

'liquid for soup' is the second definition.
'stock' can be an answer for 'soup' (stock is a kind of soup). I'm unsure of the 'liquid for' bit.

Can you help me to learn more?

(Other definitions for stock that I've seen before include "Cattle" , "shop's saleable items" , "Neck adornment" , "raw material" , "Neck garment" .)

I've seen this clue in The Telegraph.

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