Everyone's in central London (3)

I believe the answer is:

all

'everyone's' is the definition.
(I've seen this before)

'in central london' is the wordplay.
'in' says the answer is hidden in the clue.
'ALL' is hidden in the letters of 'central london'.

(Other definitions for all that I've seen before include "Quite" , "Garden passage between trees or bushes" , "Fully clad ..." , "The lot, everyone" , "100%" .)

I've seen this clue in The Telegraph.

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