Highly eager (4)
I believe the answer is:
agog
'highly eager' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for agog that I've seen before include "with eyes on stalks" , "Interested, excited and eager to know more" , "Eager - in suspense" , "In a highly excited state" , "Keen" .)