When most Geminis are born
I believe the answer is:
june
'when most geminis are born' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for june that I've seen before include "some time" , "The "flaming" month?" , "Month named after Jupiter's wife" , "Month of our summer solstice" , "Sixth month" .)