Low land, note, to the east and north (3)
I believe the answer is:
fen
'low land' is the definition.
(I've seen this in another clue)
'note to the east and north' is the wordplay.
'note' becomes 'f' (musical note).
'to the east' becomes 'E' (abbreviation).
'and' means one lot of letters go next to another.
'north' becomes 'N' (abbreviation).
'f'+'e'+'n'='FEN'
(Other definitions for fen that I've seen before include "Low-lying marshy area in England" , "One hundredth of a yuan" , "Low marshy area" , "Low-lying tract of marshy land in England" , "Low marshy land" .)