Eighteen letters back from “table” (4)

I believe the answer is:

rota

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This clue could be a double definition.

'eighteen letters' is the first definition.
'rota' can be an answer for 'letters' (thesaurus). I am not certain of the 'eighteen' bit.

'back from table' is the second definition.
'rota' can be an answer for 'table' (thesaurus). I am unsure of the 'back from' bit.

Can you help me to learn more?

(Other definitions for rota that I've seen before include "supreme Catholic court" , "Ecclesiastical tribunal" , "Duty schedule" , "Task list, roster" , "List of people taking turns" .)

I've seen this clue in the Evening Standard.

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