This column backs one up (6)

I believe the answer is:

spinal

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

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

(Other definitions for spinal that I've seen before include "Type of column" , "sort of column" , "like a column in body" , "Member of dock family with edible stems" , "affecting the back?" .)

I've seen this clue in The Globe and Mail and The Irish News.

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