this achievement is just time consuming but not difficult. you will get it eventually just by playing. if you still need this achievement when you are done with all the Classic Mode achievements, then i would suggest going to Arcade Mode as you can get a lot more fruit when the frenzy bananas appear and you don't have to worry about failing the level. if you want to check your progress you can go to Leaderboards from the main screen and press the over arrow to get to Total Fruit.
i am posting this solution for all the Total Fruit Killed achievements, but you will most likely earn some of them while working on other achievements.