I'm in a state of exhilaration (9)
I believe the answer is:
animation
'exhilaration' is the definition.
(thesaurus)
'i'm in a state' is the wordplay.
'in' indicates putting letters inside.
'state' becomes 'nation' (synonyms).
'a'+'nation'='anation'
'im' placed into 'anation' is 'ANIMATION'.
'of' is the link.
(Other definitions for animation that I've seen before include "Making of cartoons" , "Liveliness and enthusiasm" , "Cartoon technique" , "See 6" , "Being full of energy" .)