Cells with circular shape, having very small area (3)
I believe the answer is:
ova
'cells' is the definition.
(ovum is a kind of cell)
'circular shape having very small area' is the wordplay.
'circular shape' becomes 'o' (an O is a circular shape).
'having' means one lot of letters go next to another.
'very' becomes 'v' (abbreviation).
'small area' becomes 'a' (abbreviation for area often seen in geometry).
'o'+'v'+'a'='OVA'
'with' acts as a link.
(Other definitions for ova that I've seen before include "Release of women" , "Prerequisite for procreation" , "Fertility clinic stock!" , "Potential life sources" , "Likely end for Russian Fed cup players" .)