Wildly enthusiastic (4)
(Other definitions for gaga that I've seen before include "Doddery" , "Senile - slightly crazy" , "person who is senile?" , "fatuous?" , "Foolishly doting" .)
(Other definitions for avid that I've seen before include "Extremely keen" , "Greedy - enthusiastic" , "Very keen, desirous" , "Burning" , "In operation" .)