River that runs through two lakes near Keswick (7)

I believe the answer is:

derwent

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'river' is the definition.
(River Derwent in Derbyshire)

I can't explain the remainder of the clue.

(Other definitions for derwent that I've seen before include "English river" , "River; lake, --water" , "North Yorkshire river" , "Name of several rivers" , "N. Yorkshire river" .)

I've seen this clue in The Times.

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