A follower of The Crown? (8)
I believe the answer is:
royalist
'crown?' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'a follower of' is the wordplay.
I cannot quite understand how this works, but
'a' is within the answer.
'follower' could be 'ist' (I've seen this in another clue) and 'ist' is located in the answer.
'of' could be 'o' and 'o' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'the' is the link.
(Other definitions for royalist that I've seen before include "Solitary (anag.)" , "For queen" , "Civil War participant" , "One pro-monarchy" , "Monarchist" .)