One uses tactic to intercept notes from the East (8)
I believe the answer is:
employer
'one uses' is the definition.
(I've seen this before)
'tactic to intercept notes from the east' is the wordplay.
'tactic' becomes 'ploy' (a ploy is a tactic or scheme).
'to intercept' means one lot of letters goes inside another.
'notes' becomes 're me' (two musical notes, as in do-re-me).
'from the east' says the letters should be written in reverse (on a map from right to left).
'reme' reversed gives 'emer'.
'ploy' placed inside 'emer' is 'EMPLOYER'.
(Other definitions for employer that I've seen before include "One engaging staff" , "One who uses" , "One for whom people work" , "One's worked for" , "One who engages workers" .)