Hopping (5)
(Other definitions for abuzz that I've seen before include "Excitedly" , "In a state of activity" , "Excited (like a hive?)" , "Filled with humming" .)
'hopping' is the definition.
This is the entire clue.
(Other definitions for mad that I've seen before include "Extremely foolish" , "Frenzied" , "like the March Hare" , "Crazy" , "(Of a dog) rabid" .)