How would you recommend communicating with a naturally defensive coworker?
I have a coworker on my team who I sometimes need to communicate with in a professional manner. They are proven communicators as demonstrated by their contributions in team discussions and individual presentations. However, whenever I need to approach them in a 1:1 situation they tend to clam up, and adopt a defensive posture. Sometimes I am asking them for clarity about their work, or asking for their insight on a project I am working on. They aren't rude in these interactions, but they are clearly trying to offer up as little information as possible.
I have considered whether I might be too aggressive or frequent in my approaches of this person, but I don't believe this holds. I approach this person for work-related questions infrequently, and am careful to always remain cordial to help them feel at ease.
I think it's worth nothing that we are on good terms in a personal context. My (tenuous) suspicion is that this person is afraid these questions are a reflection on the quality of their work, and might be used as an attack on their professional reputation.
Any suggestions on how I can better communicate with this overly defensive colleague?