Call time finally about a Northern river (6)
I believe the answer is:
danube
'northern river' is the definition.
'Danube' can be an answer for 'river' (Danube River is an example). I'm not certain of the 'northern' bit.
'call time finally about a' is the wordplay.
'call' becomes 'dub' (both can mean to name).
'finally' indicates one should take the final letters.
'about' means one lot of letters goes inside another.
'a' becomes 'an'.
The final letter of 'time' is 'e'.
'dub'+'e'='dube'
'dube' enclosing 'an' is 'DANUBE'.
Can you help me to learn more?
(Other definitions for danube that I've seen before include "Central European river" , "River in Europe" , "River flowing through Belgrade, Budapest and Vienna" , "Viennese river" , "River flowing from Black Forest to Black Sea" .)