In this, one gets a replacement (4)

I believe the answer is:

lieu

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'in this' is the definition.
The definition suggests a singular noun which matches the answer.

'one gets a replacement' is the wordplay.
'one' becomes 'li' (I've seen this in other clues).
'gets a replacement' becomes 'eu' (I can't justify this - if you can you should give a lot more credence to this answer).
'li'+'eu'='LIEU'

Can you help me to learn more?

(Other definitions for lieu that I've seen before include "'In ..., instead (4)'" , "Place - position" , "In ... of; in exchange for" , "Stead - place" , "The substitute" .)

I've seen this clue in the Evening Standard.

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