Dump where 4x4's taken, changing directions (7)

I believe the answer is:

offload

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'dump' is the definition.
(I've seen this before)

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

(Other definitions for offload that I've seen before include "Dump" , "Get rid of (unwanted item or burden)" , "deliver goods" , "9 [JETTISON]" .)

I've seen this clue in The Telegraph.

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