Classifies positions set out by our theme (5)

I believe the answer is:

ranks

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

I can't explain the rest of the clue.

(Other definitions for ranks that I've seen before include "Lines or rows of people or things" , "Grades, in armed forces say" , "Classifies" , "Positions of seniority" , "Series of soldiers" .)

I've seen this clue in The Irish Times.

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