Graduate and soldier are wise men (4)
I believe the answer is:
magi
'wise men' is the definition.
(the three wise men from the nativity)
'graduate and soldier' is the wordplay.
'graduate' becomes 'MA' (abbreviation for Master of Arts).
'and' says to put letters next to each other.
'soldier' becomes 'gi' (term for US soldier).
'ma'+'gi'='MAGI'
'are' is the link.
(Other definitions for magi that I've seen before include "Sorcerers in ancient times" , "Travellers in NT" , "present suppliers" , "Three Wise Men of the Bible" , "The Three Kings" .)