Mike McRoberts and Six60's Matiu Walters sing waiata together in exclusive Kia Ora, Good Evening doco clip

Mike McRoberts has revealed an exclusive clip from his documentary that didn't make the final cut where he sings a waiata with a famous Kiwi face.

Kia Ora, Good Evening follows his journey as he attempts to reclaim a taonga that was lost to his whānau a generation ago - the ability to speak te reo Māori.

McRoberts' story is one of language loss, disconnection, trauma, reconnection, and re-awakening. It is set to be broadcast on Tuesday evening via Three and ThreeNow.

One moment that isn't in the documentary is him singing with Matiu Walters from Six60.

In the short clip, the pair beautifully sing a waiata together, with Walters accompanying on the guitar.

Appearing on The Project on Tuesday, McRoberts jokingly said the clip should've been used "because it would've raised the standard of waiata, for sure".

Through his documentary, he said he's finding his identity and place within te ao Māori.

"It's been very emotional, it's been a lot bigger than I would've thought it be. Very overwhelming at times as well," he told The Project.

"I've made other people throughout my career share their personal stories for the benefit of others, and that was the thing for me. I thought it would resonate with a lot of people, not just Māori, but people who are Samoan and Tongans who are trying to find their language as well, but also hopefully with non-Māori so they can see why it's so important.

"It's hard, that's the thing I want people to understand, the language trauma that goes with this, it makes it really difficult and it gets really niggly and very emotional."

Speaking te reo Māori came with its worries for McRoberts, so much so he said he felt worse anxiety going into war zones than he did having to do that.

"But that's changing now and I'm so pleased. It's been this beautiful korowai to wear since I've been learning and discovering stuff and I hope other people can take something from this as well."

Kia Ora, Good Evening premieres on Three tonight at 8:40pm.