Stockings worn by old Sugar (6)

I believe the answer is:

hexose

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'sugar' is the definition.
Both the answer and definition are singular nouns.
Maybe you can see a link between them that I can't see?

'stockings worn by old' is the wordplay.
'stockings' becomes 'hose' (I've seen this before).
'worn by' indicates putting letters inside (I've seen this in other clues).
'old' becomes 'ex' (prefix meaning former or onetime).
'hose' going around 'ex' is 'HEXOSE'.

Can you help me to learn more?

I've seen this clue in The Independent.

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