Norseman (6)
I believe the answer is:
viking
'norseman' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for viking that I've seen before include "Ancient Scandinavian adventurer" , "Scandinavian warrior" , "Norseman" , "One of the early invaders of Ireland" , "Scandinavian pirate of 8th11th centuries" .)