I have managed someone like this and it was extremely frustrating!
What's your feeling about why it is happening? Lack of time, too much workload - or lack of effort or priorities, trying to undermine you? I think this will determine the approach.
Here's what I did - it took a lot of time and intensive effort over a few weeks, but sorted the problem out permanently (though I didn't win any popularity contest). If you want to do the same, check work policies carefully and try to get a senior manager onboard first.
1.I set up a meeting to outline the issue, expressed concern without any blame. Listened carefully. Then made clear I was going to explore thoroughly what needed to be addressed and improved to make things work smoothly for the colleague in a supportive way. Was it a workload issue, time management, organisation, lack of guidance?
2.In order to address issues raised and the feedback from colleague, I gave them a time and motion study to complete, initially over the course of a week. Every half hour during the day they wrote down which task they were involved in and how long each task was taking them. They also wrote a priority list at the beginning of each day, and at end of each day a note of any deviation from the priorities with an explanation. Also any work they weren't able to complete for lack of time or too many competing demands.
If they said they didn't have time to complete the list I replied it was their top priority in order to ensure they had a manageable workload; or I could shadow them for the day/week to do it myself on their behalf - yes even on my days off!
3.Once I had this competed list, I started analysing the tasks and how long each one had taken. I also analysed their priority list - especially on days when I wasn't there to monitor myself. I also asked for a copy of their work diary commitments such as meetings for that week, so I could cross check timings and relevance. This enabled me to see if my expectations were reasonable and see whether it was a workload issue.
4.Further meeting to discuss what this had shown up. Studied their diary list with them for upcoming important tasks.
Then I set my own priority list for them to use, (if I felt theirs wasn't optimal), and my timetable for them to follow for the following week. I checked every day on this, and made them accountable for the priority list at the end of each day as before and also at the next meeting. During the day I made spot checks on the list to see if they were sticking to my timetable and if not find out why at the end of the day. I adjusted timetable for the following day with them if necessary. I presented this as a way of supporting their workload.
5.Started to ease of the monitoring once it was working effectively, and just giving the priority list and brief timetable for action every day - again monitored weekly. Any slippage we went back a stage of completing the priority list and time and motion study/detailed daily timetable given, analysing workload and priorities.
It took about 8 weeks of really intensive effort on my part to show I wasn't going to backtrack and let things slide and I was very serious about my focus and expectations, but also addressing any issues of workload, timetable or conflicting priorities they were experiencing. After this my priority list was always given top billing when I was away. They knew any ditching of my priorities would restart the whole process again.
If such an approach is acceptable in your workplace and you try it, if it doesn't work you then have a clear paper trail with evidence of intensive support you have offered, and their response and any poor performance to follow up with the competency/disciplinary route if necessary.