Crossword Genius

Reveal secret to let opposition win (4,3,4,4)

Ross

I believe the answer is:

give the game away

'reveal secret' is the definition.
(to give the game away is to reveal a secret)

I cannot understand how the rest of the clue works.

(Other definitions for give the game away that I've seen before include "Get rid of the bag" , "dispose of bag for nothing" , "show one's hand" , "resign?" , "Let cat out of bag" .)

I've seen this clue in The Independent.
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