Elliptical (4)
I believe the answer is:
oval
'elliptical' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for oval that I've seen before include "Egg shape, roughly" , "Where a duck may be broken" , "Elliptical figure" , "6D 5A [TUBE STATION]" , "Elliptical - cricket ground" .)