I have a PhD and work at a think tank. I've also worked in industry and govt, and in each of these settings, it has helped greatly to have the credential.
I work on international issues, although not development - however, my impression of that world is that hands-on experience in the developing world is practically a prerequisite. If you've done this through your research, you may need to emphasize that. If not, maybe consider doing some short-term projects that give you the on-the-ground perspective?