Harlesden’s youth centre? (3)

I believe the answer is:

les

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'harlesden's youth centre?' is the definition.
I can't tell whether this definition defines the answer.

'harlesden's youth centre?' is the wordplay.
'harlesden' becomes 'l' (I can't explain this - if you can you should believe this answer much more).
'youth' becomes 'adolescent' (I've seen this before).
'centre?' indicates the central letters (I've seen 'centre' mean this).
The central letters of 'adolescent' are 'es'.
'l'+'es'='LES'

Can you help me to learn more?

(Other definitions for les that I've seen before include "-- Dawson (late comedian)" , "French definite article" , "- Dawson, Br. comedian" , "Short boy or girl" , "-- Miserables, musical" .)

I've seen this clue in the Evening Standard.

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