Some reproductive cells (3)
I believe the answer is:
ova
'some reproductive cells' is the definition.
(ovum is a kind of reproductive cell)
This is all the clue.
(Other definitions for ova that I've seen before include "Eggs; sounds like above" , "Female reproductive cells" , "Likely end for Russian Fed cup players" , "Female gametes" , "Prerequisite for procreation" .)