Beaten by a named master (5)
I believe the answer is:
mated
'beaten' is the definition.
Both the answer and definition are adjectives. Maybe you can see a link between them that I can't see?
'by a named master' is the wordplay.
'by' says to put letters next to each other.
'a named' becomes 'ted' (I can't justify this - if you can you should give a lot more credence to this answer).
'master' becomes 'ma' (Master of Arts).
'ted' after 'ma' is 'MATED'.
Can you help me to learn more?
(Other definitions for mated that I've seen before include "given match" , "Defeated in game" , "Joined, connected" , "had sex" .)