To lose fat--hence, tone up--you will likely need to focus on your
diet. Aim for a high protein, high fiber, and low carb
diet. Because you are already very fit, if you intend to cut calories, you have to be careful how much you cut. Do not go overboard here. You only need a slight calorie deficit to make a difference (250 a day at most).
Also consider that sometimes the "fat" we think we have is actually just water.