Lacking direction, driver ultimately unable to deliver milk (10)

I believe the answer is:

rudderless

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

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

(Other definitions for rudderless that I've seen before include "Lacking direction" , "Without steering mechanism" , "Unable to provide guidance" , "not yielding power to steer" , "Having lost control" .)

I've seen this clue in The Guardian.

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