Regular correspondence between sides (8)

I believe the answer is:

symmetry

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'regular correspondence' is the definition.
'symmetry' can be an answer for 'correspondence' (synonyms). I am not certain of the 'regular' bit.

I can't explain the rest of the clue.

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(Other definitions for symmetry that I've seen before include "Proportion; beauty of form" , "shapely attribute" , "Mirrored disposition about axis" , "Arrangement of parts in pleasing proportions" , "Regularity of shape" .)

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

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