Boy returning with temperature given strange patent remedy (7)

I believe the answer is:

nostrum

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'patent remedy' is the definition.
(term for non-prescription medicine)

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for nostrum that I've seen before include "answer to all problems!" , "Hypothetical remedy for all ills" , "Quack medicine - run most (anag)" , "Phoney panacea" , "Quack cure" .)

I've seen this clue in The Telegraph.

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