If your boss isn’t a good guide and doesn’t support you, it’s up to you to get what you need. If you can easily get in touch with someone who used to work for your boss, invite him out for coffee. Explain that you’re eager to develop in your role, and that you’d like to pick his brain about working with and learning from your boss.
Pitch it as a tutorial, not as a gripe session: See if he can share insights about her mentoring style, for example, and tips on how to earn her trust.
Even if you feel safe confiding in this person, assume that anything you say could make its way back to your boss and edit yourself accordingly.
Adapted from the HBR Guide to Office Politics.