Eagerly expectant (4)
I believe the answer is:
agog
'eagerly expectant' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for agog that I've seen before include "Very eager (in anticipation)" , "In a highly excited state" , "In excited eagerness" , "Expectant, eager" , "Eager and wide-eyed" .)