Excitement where party drops leader (7)
I believe the answer is:
arousal
'excitement' is the definition.
(thesaurus)
'party drops leader' is the wordplay.
'party' becomes 'carousal' (I've seen this before).
'drops leader' means to remove the first letter (I've seen 'dropping leader' mean this).
'carousal' with its initial letter taken away is 'AROUSAL'.
'where' is the link.
(Other definitions for arousal that I've seen before include "Sexual excitement" , "heating?" , "Act of awakening" , "Drinking spree" , "Awakening; stimulation" .)