Bethlehem visitors (12)
'bethlehem visitors' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for magi that I've seen before include "Wise men who were guided by a star" , "Three Wise Men from the East" , "Sorcerers in ancient times" , "Christmas travellers" , "Wise men, visitors to Bethlehem" .)