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.