Clear river keeps running at speed (9)

I believe the answer is:

exonerate

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'clear' is the definition.
(to clear of criminal charges)

'river keeps running at speed' is the wordplay.
'river' becomes 'exe' (River Exe).
'keeps' means one lot of letters goes inside another (inserted letters are kept inside).
'running at' becomes 'on' (location. I am not sure about the 'running' bit.).
'speed' becomes 'rate' (both can mean pace).
'exe' enclosing 'on' is 'exone'.
'exone'+'rate'='EXONERATE'

Can you help me to learn more?

(Other definitions for exonerate that I've seen before include "Release" , "free of charge" , "Declare to be free from blame" , "Justify" , "Excuse" .)

I've seen this clue in The Sun.

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