Itinerant person (4)
(Other definitions for hobo that I've seen before include "Deer, situated at the back" , "Bum" , "Vagrant (US)" , "Vagrant (American)" , "American tramp" .)
(Other definitions for migrant that I've seen before include "Person moving abroad" , "Person moving countries" , "Person who has moved residence to another place" , "Animal moving with the seasons" , "Transient" .)
'itinerant person' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for drifter that I've seen before include "Person of no fixed abode" , "Fishing-boat" , "One who moves about aimlessly" , "Fishing boat; hobo" , "one unsettled" .)