Result united leaderless country, lasting (9)
I believe the answer is:
endurance
'country lasting' is the definition.
I can't tell whether this defines the answer.
'result united leaderless' is the wordplay.
'result' becomes 'end' (I've seen this in other clues).
'united' becomes 'U' (abbreviation).
'leaderless' becomes 'rance' (I can't explain this - if you can you should give a lot more credence to this answer).
'end'+'u'+'rance'='ENDURANCE'
Can you help me to learn more?
(Other definitions for endurance that I've seen before include "ability to survive" , "Patient toleration" , "Tenacity" , "Stoical coping with hardship" , "Ability to stay a difficult course, courage" .)