Traveler (4)
I believe the answer is:
goer
'traveler' is the definition.
(I know that goer is a type of migrant)
This is all the clue.
(Other definitions for goer that I've seen before include "Lively energetic person" , "Lively person -- feasible idea" , "Energetic type" , "one trying to succeed" , "Someone lively" .)