In Africa it flows down meandering line (4,4)
I believe the answer is:
blue nile
'in africa it flows' is the definition.
I can't tell whether this defines the answer.
'down meandering line' is the wordplay.
'down' becomes 'blue' (both can mean sad).
'meandering' indicates anagramming the letters.
'line' anagrammed gives 'nile'.
'blue'+'nile'='BLUE NILE'
Can you help me to learn more?
(Other definitions for blue nile that I've seen before include "River flowing from Lake Tana (Ethiopia) to Khartoum (Sudan)" , "There's also a white river" , "African river" .)