Surprise cut short on river (6)

I believe the answer is:

amazon

'river' is the definition.
(Amazon is an example)

'surprise cut short on' is the wordplay.
'surprise' becomes 'amaze' (amazing is a kind of surprising).
'cut short' means to remove the last letter.
'amaze' with its last letter removed is 'amaz'.
'amaz'+'on'='AMAZON'

(Other definitions for amazon that I've seen before include "Encourage, ask" , "Strong, aggressive woman" , "Female warrior of Greek myth" , "Female warrior - parrot - South American river" , "Fighting woman from a great river" .)

I've seen this clue in The Sun and The Telegraph.

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