Ova or roe (4)
I believe the answer is:
eggs
I believe this clue is a double definition.
'ova' is the first definition.
(egg is a kind of ovum)
'roe' is the second definition.
(I've seen this before)
(Other definitions for eggs that I've seen before include "Roe" , "Those scrambled, boiled, poached or fried" , "Ova" , "Wherein soldiers enter" , "Ovoid objects" .)