Important person you play roulette with (3,5)

I believe the answer is:

big wheel

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

'important person' is the definition.
(I know that big wheel is a type of important person)

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for big wheel that I've seen before include "Fairground ride" , "Fairground attraction - VIP" , "going round in London" , "Important person - fair attraction" , "Amusement as London Eye" .)

I've seen this clue in the Evening Standard.

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