Not easily disturbed by question and answer in rising river (7)
I believe the answer is:
equable
'not easily disturbed' is the definition.
'question and answer in rising river' is the wordplay.
'question and answer' becomes 'qua' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'rising' says the letters should be written backwards (going up in a down clue).
'river' becomes 'elbe' (river in Germany).
'elbe' in reverse letter order is 'eble'.
'qua' placed inside 'eble' is 'EQUABLE'.
'by' acts as a link.
Can you help me to learn more?
(Other definitions for equable that I've seen before include "Not extreme" , "Not easily angered" , "Cool" , "Calm, even-tempered" , "composed" .)