Plough through a translation from Latin (5,4)

I believe the answer is:

great bear

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

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

(Other definitions for great bear that I've seen before include "visible in the night sky" , "Large animal - same as 7" , "star group" , "'Large ursine in the heavens (5,4)'" , "Plough constellation" .)

I've seen this clue in The Times.

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