Describe an ongoing problem at your current or former employer that you were able to overcome.
Every place of employment will have it's challenges. Talk to the interviewer about a specific issue that you were able to overcome in your previous role. Be sure to remain positive. The interviewer isn't looking for you to dump all over your current boss or coworkers, especially if you're applying for a job with a competitor, so avoid complaining or saying negative things about your previous employer or co-workers.
"In my most recent position we had an ongoing problem with different offices fighting with each other over who would work on a specific project. One office's work wasn't up to our high standards and we were slipping behind schedule, but they kept pushing to be included in the project. We had to have a difficult conversation with their branch manager and explain what needed to be done to keep the project on track."