Valley of the Daleks (4)

I believe the answer is:

dale

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'valley' is the definition.
(dale is a kind of valley)

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

(Other definitions for dale that I've seen before include "Valley, particularly in Northern England" , "Up hill and down . . . ." , "Lead into poetic valley" , "Low ground" , "An English valley" .)

I've seen this clue in the Evening Standard.

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