Found out emigration drove out millions (9)
I believe the answer is:
originate
'found' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for originate that I've seen before include "Launch" , "Stem" , "Create; begin" , "Cause to begin, be the first" , "Come into existence" .)