A dark evening suit designed for dancers

I believe the answer is:

nightclubs

I'm a little stuck... Click here to teach me more about this clue!

'designed for dancers' is the definition.
Although both the answer and definition are plural nouns, I don't understand how they can define each other.

'a dark evening suit' is the wordplay.
'a dark evening' becomes 'night' (I've seen this before. I am not sure about the 'dark' bit.**).
'suit' becomes 'clubs' (I've seen this before).
'night'+'clubs'='NIGHTCLUBS'

Can you help me to learn more?

(Another definition for nightclubs that I've seen is " entertaining here?".)

I've seen this clue in the Irish Times.

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