Do lots of seated calve raises...
just like pectoralis minor and brachialis the soleus is one of those deeper lying muscles, that when fully developed will push the muscles on top (in this case the gastro) of that more to the surface and further appart , hence more seperation/definition.....
Also the seated calve raise call upon the tibialis anterior for stabillisation and this will give you wide sweepy calves viewed from the front....
Dropping BF is also a way , best to take both ways...
Funny thing is that you see sometimes fat people with big hard veiny calves , guess the distribution of fatcells is in many times uneven throughout the body, genetically determined....