Yes. You can overclock an AMD A4–5300 APU.
To overclock your CPU you would use AMD Overdrive. Here is a video that shows you what to do, step-by-step. Please Note: This video is not mine
Be sure do use baby steps, overclock a little bit, use the stability test (as seen in the video) and test it out with a game or whatever else you plan to do on your PC and see if your PC overheats. Then you can go back and push it up a little more.
WARNING / DISCLAIMER: Overclocking your CPU, GPU, RAM will increase the heat production from the part(s) you overclock. Overheating is the #1 reason PC parts die. There is a chance you will kill your AMD APU or whatever else you try to overclock. Nobody on this site, including myself is responsible if you kill your AMD APU or if it causes other problems like your computer will not boot properly and you can’t even get Windows to load. If you get any of these problems or some other issue I did not mention, you have to take it to a tech in your area so he can fix what you broke, which will probably cost between $250-$400 with parts and labor (It might even cost you more).