Serving of Navratilova lost shape (4)

I believe the answer is:

oval

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

'serving of navratilova lost' is the wordplay.
'serving of' indicates the answer is hidden within the clue.
'OVAL' is hidden in the letters of 'navratilova lost'.

(Other definitions for oval that I've seen before include "London cricket ground" , "Elliptical figure" , "Cricket ground - presidential office" , "Easter gift" , "Ellipse" .)

I've seen this clue in The Guardian.

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