Soccer champion secured opening goal with good prosthesis (6)

I believe the answer is:

pegleg

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'prosthesis' is the definition.
(pegleg is a kind of prosthesis)

I cannot understand how the rest of the clue works.

(Other definitions for pegleg that I've seen before include "Long John Silver, for instance" , "Person with a wooden limb" .)

I've seen this clue in the Sydney Morning Herald.

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