A crew's route up the Thames? (11)

I believe the answer is:

watercourse

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'the thames?' is the definition.
I can't judge whether this defines the answer.

'a crew's route up' is the wordplay.
'up' indicates anagramming the letters.
'a'+'crews'+'route'='acrewsroute'
'acrewsroute' anagrammed gives 'WATERCOURSE'.

Can you help me to learn more?

(Other definitions for watercourse that I've seen before include "Test" , "Brook, stream, etc" , "Eg, stream or river" , "Stream, river, channel" .)

I've seen this clue in The Independent.

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