HIIT. High intensity interval training is the best way to go if you are short on time, as this will increase your fitness levels, and beneficial in burning fat in a short and intense workout. Aim for 14-30 mins each seesion.
example could be sprinting 30 secs then walking 30 secs, and then repeat.
Also, you may find it helpful to strengthen the core.
Diet is very important as well.