Trio of magicians (4)
I believe the answer is:
magi
'magicians' is the definition.
(magus is a kind of magician)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for magi that I've seen before include "men on special quest" , "The three Wise Men of the gospels" , "Persian wise men" , "The three Wise Men of Bethlehem" , "Wise men who were guided by a star" .)