Imperial chief, leader of nation in comfort with uniform on (9)
I believe the answer is:
kitchener
'uniform on' is the definition.
The definition suggests a singular noun which matches the answer.
'imperial chief leader of nation in comfort' is the wordplay.
'imperial chief' becomes 'kit' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'leader of' suggests taking the first letters.
'in' means one lot of letters goes inside another.
'comfort' becomes 'cheer' (cheer can mean to comfort or gladden someone).
The first letter of 'nation' is 'n'.
'n' inserted into 'cheer' is 'chener'.
'kit'+'chener'='KITCHENER'
'with' acts as a link.
Can you help me to learn more?
(Other definitions for kitchener that I've seen before include "'Your country needs you' soldier" , "cooker" , "Earl drowned in Hampshire" , "British field marshall, whose image appeared on WWI recruitment posters" , "soldier who pointed his finger" .)