Billionaire has these guarding his entrance? (5)

I believe the answer is:

gates

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'billionaire' is the definition.
(tech billionaire Bill Gates)

I don't understand the rest of the clue.

(Other definitions for gates that I've seen before include "Microsoft's Bill?" , "Moveable barriers" , "Billionaire Bill - openers" , "Rich American" , "Movable barriers in fence or wall" .)

I've seen this clue in The Guardian.

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