River keeps running at speed, being clear (9)
I believe the answer is:
exonerate
'being clear' is the definition.
(I've seen this before)
'river keeps running at speed' is the wordplay.
'river' becomes 'exe' (River Exe).
'keeps' indicates putting letters inside.
'running' becomes 'on' (I've seen this in other clues).
'at speed' becomes 'rate' (I can't justify this - if you can you should give a lot more credence to this answer).
'exe' placed around 'on' is 'exone'.
'exone'+'rate'='EXONERATE'
Can you help me to learn more?
(Other definitions for exonerate that I've seen before include "Acquit" , "let off the hook" , "Justify" , "Declare to be free from blame" , "Discharge" .)