Set aside poll after opening (5)

I believe the answer is:

allot

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'set aside' is the definition.
(I've seen this in another clue)

I don't understand the rest of the clue.

(Other definitions for allot that I've seen before include "Parcel out, assign" , "Assign a share" , "Designate; sounds like much" , "Award (share, task)" , "Assign (to someone)" .)

I've seen this clue in the Sydney Morning Herald.

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