Hi Hazelnut, I think cankles are pretty much genetics tbh, my cousin has cankles at size 6! You could ask at the gym for a programme to sculpt your legs maybe? Build up the calf for a more defined ankle if you see what I mean...or view it as an excuse to buy some amazing boots! I have the opposite problem of skinny ankles and big calves and use it as an excues to buy gorgeous boots from duo
I also think that cankles look really sexy if you wear a traditional stiletto court shoe with quite a flared skirt to just below the knee!