Crossword Genius

Spindles without even a flank (4)


I believe the answer is:

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

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for side that I've seen before include "by no means a front", "group of players", "long forgotten", "party", "Left or right, say".)

I've seen this clue in Sydney Morning Herald.