Ground to shape? (4)
I believe the answer is:
oval
This clue is a double definition.
'ground' is the first definition.
(cricket ground)
'shape?' is the second definition.
(oval is a kind of shape)
'to' is the link.
(Other definitions for oval that I've seen before include "form of an egg" , "Elliptical figure" , "sports ground" , "Test site" , "Squashed circle" .)