If I remember correctly ClearAll will wait until all monsters are dead, then it will trigger a mana refill, and once that is done it will tell the Druid to stop using wild growths.
There are two different wild growth labels, both are followed by two numbers which are x and y coordinates. One of the labels will make the druid surround itself with wild growths while the other will only cast wild growth on the coordinates specified by the label. Both labels use the specified x and y coordinates to determine which wild growth to cut down with the machete (only really necessary on retro though).
There are also some one-liners for casting wild growth in the script. However, those aren't really necessary, but rather an attempt at optimizing the speed of the first cast.