Bug-eyed (4)
I believe the answer is:
agog
'bug-eyed' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for agog that I've seen before include "Interested, excited and eager to know more" , "Very eager (to see/hear)" , "Eager - in suspense" , "Mouth open" , "In excited eagerness" .)