Settle in another country
(Other definitions for immigrate that I've seen before include "Enter the country permanently" , "Come into foreign country as permanent resident" , "come in to land" , "Come to reside in a country" , "Permanently move into a country" .)
'settle in another country' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for emigrate that I've seen before include "don't come back!" , "Leave the country to settle abroad" , "Go to live and work in another country" , "Move abroad" , "Permanently leave" .)