Eccles is boring celebrity setter about subject (8)

I believe the answer is:
liegeman
'eccles' is the definition.
Both the answer and definition are singular nouns.
Maybe there's a link between them I don't understand?
'boring celebrity setter about subject' is the wordplay.
'boring celebrity setter' becomes 'man' (I can't justify this - if you can you should believe this answer much more).
'about' means one lot of letters go next to another.
'subject' becomes 'liege' (I've seen this before).
'man' after 'liege' is 'LIEGEMAN'.
'is' is the link.
Can you help me to learn more?
(Other definitions for liegeman that I've seen before include "Loyal follower" , "A loyal person" , "Vassal, subject" , "Person serving lord" .)
