Schoolboy returned note to Scotsman (7)
I believe the answer is:
etonian
'schoolboy' is the definition.
(I've seen this before)
'returned note to scotsman' is the wordplay.
'returned' says the letters should be written backwards.
'to scotsman' becomes 'ian' (common Scottish name).
'note' backwards is 'eton'.
'eton'+'ian'='ETONIAN'
(Other definitions for etonian that I've seen before include "Public school kid" , "One educated at famous public school" , "student in establishment?" , "Relating to one particular school" , "Alumnus of famous English school" .)