Traditional Platonic Academy
I believe the answer is:
old school
'traditional' is the definition.
(I've seen this before)
'platonic academy' is the wordplay.
'platonic' becomes 'old' (I am not sure about this - if you are sure you should believe this answer much more).
'academy' becomes 'school' (I've seen this before).
'old'+'school'='OLD SCHOOL'
Can you help me to learn more?
(Other definitions for old school that I've seen before include "Of people favouring traditional ideas" , "Conservative thinkers" , "Those who think traditionally" , "Doing things the same way as before" , "square" .)