A shade right-wing, like Edward III primarily (5,4)
I believe the answer is:
royal blue
'a shade' is the definition.
(shade of blue)
'right-wing like edward iii primarily' is the wordplay.
'right-wing' becomes 'blue' (blue is the colour of the Conservative Party).
'like edward iii' becomes 'royal' (I can't explain this - if you can you should believe this answer much more).
'primarily' means one lot of letters go next to another.
'blue' after 'royal' is 'ROYAL BLUE'.
Can you help me to learn more?
(Other definitions for royal blue that I've seen before include "A shade Conservative" , "Deep rich shade of colour" , "(Regal?) colour" , "Queen's shade?" , "Dark colour" .)