Couple making king new centre of family tree (7)
I believe the answer is:
linkage
'centre of family tree' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'couple making king new' is the wordplay.
'couple' becomes 'link' (couple can mean to link or join).
'making king new' becomes 'age' (I am not sure about this - if you are sure you should believe this answer much more).
'link'+'age'='LINKAGE'
Can you help me to learn more?
(Other definitions for linkage that I've seen before include "Connection, coupling" , "Connection, bond" , "where the join is" , "System of connections" , "Part of mechanism" .)