Kelly Clarkson has apologised to the cast and crew of 'The Rookie' after making a cameo appearance on the show

The singer said on 'The Kelly Clarkson Show': "Oh my God, I was terrified. I have to apologise to that cast and crew. I was terrified.

"'The Rookie', they invited me, and here's the thing - I'm a huge, like, I've been a fan of Nathan Fillion since 'Castle'. I already get nervous on sets, but then he made me more nervous than I have ever been on a set ... I was an idiot on that set."

Kelly would love to appear on 'Only Murders in the Building', the hit TV show that stars Selena Gomez, Martin Short and Steve Martin.

But Kelly now accepts that she's not suited to walk-on roles.

She said: "Maybe 'Only Murders in the Building' because I love 'Only Murders'. But no, I've seen the level in which that show [operates] - I am not a walk-on, so I actually take that back.

"That's never been my goal to be like, 'Oh, I want to do all these things.' I'm just a big fan."

Kelly previously admitted that she struggled to contain her nerves while shooting 'The Rookie'.

The pop star was happy to return to more comfortable surroundings after she shot her cameo.

Kelly said in 2023: "It was so nice and it was really easy and fun and I love this group even more now. But I am glad that I am leaving and the actors are staying and acting."