Evoke a river: one in the north east (6)
I believe the answer is:
arouse
'evoke' is the definition.
(synonyms)
'a river one in the north east' is the wordplay.
'river' becomes 'r' (abbreviation for river).
'one in the north east' becomes 'ouse' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a'+'r'+'ouse'='AROUSE'
Can you help me to learn more?
(Other definitions for arouse that I've seen before include "Excite, awaken" , "Awake from sleep" , "Excite; wake from sleep" , "Excite; provoke" , "Galvanize" .)