Sources of Cointreau or spirits, dispensing litre (7)
I believe the answer is:
oranges
'or spirits dispensing litre' is the definition.
I can't judge whether this definition defines the answer.
'sources of cointreau' is the wordplay.
'sources' suggests taking the first letters (I've seen 'source of' mean this).
'cointreau' becomes 'ranges' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The initial letter of 'of' is 'o'.
'o'+'ranges'='ORANGES'
Can you help me to learn more?
(Other definitions for oranges that I've seen before include "Navel, blood and Seville are all varieties of these" , "They are not the only fruit, wrote Jeanette Winterson" , "'Mandarins, say (7)'" , "Gear son up for fruit" , "Mandarins, satsumas etc." .)