Weakness shown by patriarchal seat of old empire? (10)
I believe the answer is:
incapacity
'weakness' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Maybe you can see a link between them that I don't see?
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for incapacity that I've seen before include "Lack of power or ability" , "Lack of required skills" , "Helplessness" , "Lack of authority" , "Powerlessness" .)