Excited, as to come out (8)
I believe the answer is:
comatose
'out' is the definition.
(thesaurus)
'excited as to come' is the wordplay.
'excited' indicates anagramming the letters.
'as'+'to'+'come'='astocome'
'astocome' anagrammed gives 'COMATOSE'.
(Other definitions for comatose that I've seen before include "Deeply unconscious" , "Somnolent" , "Very drowsy, perhaps unconscious" , "Fast asleep" , "Senseless, unconscious" .)