Wherein kings and queens join a friend for cards? (7)

I believe the answer is:

palaces

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'wherein kings and queens join a' is the definition.
I can't tell whether this definition defines the answer.

'friend for cards?' is the wordplay.
'friend' becomes 'pal' (pal can mean a friend).
'for' is a charade indicator (letters next to each other).
'cards?' becomes 'aces' (ace is a kind of card).
'pal'+'aces'='PALACES'

Can you help me to learn more?

(Other definitions for palaces that I've seen before include "Offical residences of sovereigns" , "Royal residences" , "kings and queens here?" .)

I've seen this clue in the Evening Standard.

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