Legal disqualification on the crown on a major town (10)
I believe the answer is:
incapacity
'legal disqualification on the crown on a major town' is the definition.
I can't judge whether this definition defines the answer.
'disqualification on the crown on a major town' is the wordplay.
'disqualification on' becomes 'in' (I can't justify this - if you can you should give a lot more credence to this answer).
'the crown' becomes 'cap' (I've seen this in another clue).
'on' is a charade indicator (letters next to each other).
'major town' becomes 'city' (a city is a major settlement).
'in'+'cap'+'a'+'city'='INCAPACITY'
Can you help me to learn more?
(Other definitions for incapacity that I've seen before include "Disability" , "Powerlessness" , "Lack of required skills" , "Helplessness" , "Lack of authority" .)