Treasure for the GI? (6,2,5)

I believe the answer is:

pieces of eight

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'the gi?' is the definition.
(I've seen this in another clue)

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

(Other definitions for pieces of eight that I've seen before include "Old coins; '---!' (Long John Silver's parrot)" , "2 and 6 perhaps" , "Old Spanish silver coins" , "Spanish dollars" , "In old money" .)

I've seen this clue in The Independent.

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