What may be thrown in Devon river (4)

I believe the answer is:

dart

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'devon river' is the definition.
(River Dart in Devon)

I don't understand how the remainder of the clue works.

(Other definitions for dart that I've seen before include "shift fast" , "one destined to go on board?" , "Devon river - bound - race" , "flash" , "Small pointed projectile" .)

I've seen this clue in The Times.

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