American actor, Matt, becomes a drifter (5)
I believe the answer is:
nomad
'drifter' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for nomad that I've seen before include "one of those with no fixed home" , "Unsettled character" , "Member of a wandering pastoral community" , "wandering type" , "Unsettled type" .)