Not binders, but seating arrangements (5)

I believe the answer is:

tiers

I'm a little stuck... Click here to teach me more about this clue!

'arrangements' is the definition.
(tier is a kind of arrangement)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for tiers that I've seen before include "drawers?" , "I rest in layers" , "Layers, levels" , "Row upon row" , "Layers, strata" .)

I've seen this clue in the Evening Standard.

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