Eagerly, enthusiastically (6)
I believe the answer is:
avidly
This clue is a double definition.
'eagerly' is the first definition.
(I've seen this in another clue)
'enthusiastically' is the second definition.
(I've seen this before)
(Other definitions for avidly that I've seen before include "Keenly, eagerly" , "With keenness" , "with enthusiasm" , "Eagerly, enthusiastically" , "With eagerness" .)