Rees-Mogg, perhaps Spooner's anaemic twin (5-6)
I believe the answer is:
right-winger
'twin' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for right-winger that I've seen before include "team member" , "Blue" .)