As a journalist, you will write stories and articles where interviewing a subject matter expert, an influencer, or even a witness, is a requirement. The interviewer would like to know that you can conduct interviews without feeling shy or incapable.
If you have experience conducting one-on-one interviews, you can discuss that experience by talking about the most challenging conversation you have ever undertaken.
If you do not have experience with one-on-one interviews, discuss any training you have received or mention how capable you feel doing interviews.