Honestly three sheets to the wind, under the table (2,3,3)

I believe the answer is:

on the sly

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'under the table' is the definition.
(I've seen this before)

'honestly three sheets to the wind' is the wordplay.
'honestly' can be anagrammed to 'ON THE SLY'.
But, I am not clear how the anagram is indicated.

Can you help me to learn more?

(Other definitions for on the sly that I've seen before include "Honestly (anag) - dishonestly" , "under cover" , "Secretly or furtively" , "Behind someone's back" , "Surreptitiously" .)

I've seen this clue in The Telegraph.

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