Shape of girls' night out consuming Prosecco primarily to order after child's play (8)

I believe the answer is:

heptagon

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'shape' is the definition.
(heptagon is a kind of shape)

I cannot understand how the remainder of the clue works.

(Other definitions for heptagon that I've seen before include "A geometric figure with seven sides" , "Seven-sided figure" , "Seven-sided object" , "Seven-sided shape" .)

I've seen this clue in the Irish Times.

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