What replenishes Losec on dwindling reserves (6,4)

I believe the answer is:

second wind

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'reserves' is the definition.
Both the definition and answer are singular nouns.
Maybe they are linked in a way I don't understand?

'what replenishes losec on dwindling' is the wordplay.
'SECOND WIND' is hidden in amongst the letters.
However, I am not sure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for second wind that I've seen before include "Renewed energy in effort" , "Renewed vigour" , "Distance runners need to get it" , "playing perhaps but not from top brass" , "Renewed energy to carry on" .)

I've seen this clue in The Independent.

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