Saying More
You can start a response at the viva with, “Well, my supervisor told me to…”
You always need to say something more.
You could talk about why your supervisor advised that. You could reference what stage of your PhD this was. You could unpick what you had already tried. You could say more about how you applied the suggestion. Depending on the situation you might even be talking about what didn’t work and what you then had to do instead!
Your examiners know that you’ve had support. They expect that you were given guidance or told what to do at many stages of your PhD. You can say that but you need to say more to show your role and efforts.