It records speed on river (7)

I believe the answer is:

dashcam

'it records' is the definition.
(a dashcam records footage)

'speed on river' is the wordplay.
'speed' becomes 'dash' (dashing is a kind of speeding).
'on' says to put letters next to each other.
'river' becomes 'Cam' (river in Cambridge, England).
'dash'+'cam'='DASHCAM'

I've seen this clue in The Guardian.

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