The boys like roulette (7)

I believe the answer is:

russian

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'roulette' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for russian that I've seen before include "Muscovite, maybe" , "Slav" , "Native of St Petersbourg, say" , "Eg, Moscow native" , "Slavonic tongue" .)

I've seen this clue in the Evening Standard.

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