English change course overturning old magistrate (5)
I believe the answer is:
reeve
'old magistrate' is the definition.
(I've seen this before)
'english change course overturning' is the wordplay.
'english' becomes 'e' (abbreviation).
'change course' becomes 'veer' (I've seen this before).
'overturning' says the letters should be written in reverse.
'e'+'veer'='eveer'
'eveer' back-to-front is 'REEVE'.
(Other definitions for reeve that I've seen before include "Former official - female ruff" , "Pass the end of a rope through the bailiff" , "fasten rope" , "High official" , "US actor" .)