The shape of a cricket ground (4)
I believe the answer is:
oval
I believe this is a double definition.
'the shape' is the first definition.
(oval is a kind of shape)
'a cricket ground' is the second definition.
(London cricket ground)
'of' is the link.
(Other definitions for oval that I've seen before include "sports ground" , "Shaped like an egg" , "Rounded like an egg" , "Egg shape, roughly" , "Race track" .)