Chief magistrate, going north, to change direction at Spain (5)
I believe the answer is:
reeve
'chief magistrate' is the definition.
'reeve' can be an answer for 'magistrate' (I've seen this before). I'm unsure of the 'chief' bit.
'going north to change direction at spain' is the wordplay.
'going north' says the letters should be written backwards.
'to change' becomes 'eve' (I can't explain this - if you can you should give a lot more credence to this answer).
'direction' becomes 'r' (r is abbreviation for right).
'at' is a charade indicator (letters next to each other) (I've seen this in other clues).
'spain' becomes 'e' (abbreviation for Espana).
'r' put after 'e' is 'er'.
'eve'+'er'='eveer'
'eveer' back-to-front is 'REEVE'.
Can you help me to learn more?
(Other definitions for reeve that I've seen before include "Ancient magistrate" , "old-fashioned official" , "Chief magistrate, formerly" , "The bailiff to run a rope through" , "Old judge" .)