Lady singer opens games in Irish sports governing body (4)

I believe the answer is:

gaga

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'lady singer' is the definition.
(Lady Gaga the singer)

I cannot understand how the remainder of the clue works.

(Other definitions for gaga that I've seen before include "Slang for crazy - apply a gag" , "crackers" , "Slangily crazy or senile" , "Doddery" , "Lady who sings" .)

I've seen this clue in The Irish Times.

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