Chicago girls hide in excited eagerness (4)
I believe the answer is:
agog
'in excited eagerness' is the definition.
(I've seen this before)
'chicago girls hide' is the wordplay.
'hide' says the answer is hidden in the clue.
'AGOG' is hidden within 'chicago girls'.
(Other definitions for agog that I've seen before include "Bug-eyed" , "Interested, excited and eager to know more" , "Wide-eyed and fascinated" , "Eagerly expectant" , "Eager, avid" .)