Wherein to lie with false-hearted mien? (4)

I believe the answer is:

lair

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'wherein to lie' is the definition.
I can't tell whether this definition defines the answer.

'with false-hearted mien?' is the wordplay.
'with' says to put letters next to each other.
'hearted' says to take the centre.
'mien?' becomes 'air' (I've seen this before).
The middle letter of 'false' is 'l'.
'l'+'air' is 'LAIR'.

Can you help me to learn more?

(Other definitions for lair that I've seen before include "Rail about wild animal's home" , "mire where he lives" , "Rail around animal's den" , "enclosure" , "Secret base" .)

I've seen this clue in the Evening Standard.

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