Eager, enthusiastic (4)
(Other definitions for avid that I've seen before include "Keen or greedy" , "Extremely enthusiastic" , "'Eager, zealous (4)'" , "Burning" , "Greedy like diva" .)
I believe this is a double definition.
'eager' is the first definition.
(I've seen this before)
'enthusiastic' is the second definition.
(I've seen this before)
(Other definitions for keen that I've seen before include "Anxious" , "Longing" , "devoted" , "Eager; wail in grief" , "Eager; dirge" .)