Australia face Ireland in Belfast on Thursday in what will be the first one-day international since beating New Zealand in the World Cup final in Melbourne in March.
It will also be Australia's first match since Clarke retired from all international cricket after the fifth and final Test against England at The Oval last week.
Australia won by an innings and 46 runs but victory in south London came too late to save the Ashes, with England winning the five-match series 3-2.
"I'm very excited," Smith told travelling Australian media in Belfast on Wednesday.
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"Obviously, I've known for a little while now that I was going to be taking over the one-day squad, so I've been working pretty hard and preparing (for) everything coming up,"
He added: "The last time this group was together, we won a World Cup, so I don't think we have to change a whole heap. We're currently No.1 in the world. I think for us now, it's just about raising that bar and continuing to get better each day."
"I guess it's a new era in a way for Australian cricket," said Smith. "But they're really excited and I'm really excited to see them do well on this tour.