Was behind but determined (6)

I believe the answer is:

dogged

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

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

(Other definitions for dogged that I've seen before include "Stubborn or determined in canine manner" , "Worried" , "Resolute; trailed" , "Followed - stubborn" , "Stubbornly persisting" .)

I've seen this clue in The Guardian.

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