Win support for essential truth from small part of England (7)
I believe the answer is:
rutland
'part of england' is the definition.
(I know that Rutland is part of England)
'win support for essential truth' is the wordplay.
'win' becomes 'land' (both can mean to secure or obtain).
'support for' is a charade indicator (letters next to each other) (in a down clue, some letters 'support' others).
'essential truth' becomes 'rut' (I can't explain this - if you can you should give a lot more credence to this answer).
'land' after 'rut' is 'RUTLAND'.
'from small' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for rutland that I've seen before include "England's smallest county" , "Tiny county" , "Smallest of the historical English counties" , "Oakham area" , "East Midlands county" .)