Memo school brought up (4)
I believe the answer is:
note
'memo' is the definition.
(thesaurus)
'school brought up' is the wordplay.
'school' becomes 'eton' (famous UK public school).
'brought up' is a reversal indicator (down clues only).
'eton' written backwards gives 'NOTE'.
(Other definitions for note that I've seen before include "Observe, record" , "Record - piece of music" , "Brief letter - distinction" , "Make a record of" , "Pay close attention to" .)