Ancient priests in one school, coming from the east (4)
I believe the answer is:
magi
'ancient priests' is the definition.
'magi' can be an answer for 'priests' (magus is a kind of priest). I am not sure about the 'ancient' bit.
'one school coming from the east' is the wordplay.
'one' becomes 'i' (Roman numeral).
'school' becomes 'gam' (both can refer to a group of whales).
'coming from the east' shows that the letters should be reversed in order (letters written from right to left or east to west).
'i'+'gam'='igam'
'igam' backwards is 'MAGI'.
'in' is the link.
Can you help me to learn more?
(Other definitions for magi that I've seen before include "Three Wise Men from the East" , "Star witnesses" , "Wise men, visitors to Bethlehem" , "Persian wise men" , "present suppliers" .)