A flat, say, turned over in school (4)
I believe the answer is:
eton
'school' is the definition.
(famous UK public school)
'a flat say turned over' is the wordplay.
I cannot quite see how this works, but
'over' could be 'on' (physically on top of) and 'on' is present in the answer.
This may be the basis of clue (or it may be nonsense).
'in' acts as a link.
Can you help me to learn more?
(Other definitions for eton that I've seen before include "Posh British public school" , "Public school near Windsor" , "School near Slough" , "learn here?" , "Town opposite Windsor on the Thames" .)