Crossword Genius

How overcrowding very annoyingly starts in cells (3)

Ross

I believe the answer is:

ova

'cells' is the definition.
(ovum is a kind of cell)

I cannot understand how the remainder of the clue works.

(Other definitions for ova that I've seen before include "Release of women" , "Female egg-cells" , "Female gametes" , "Female egg cells" , "Likely end for Russian Fed cup players" .)

I've seen this clue in The Times.
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