Old party to get excited endlessly, making a stink (7)
I believe the answer is:
odorous
'making a stink' is the definition.
'old party to get excited endlessly' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'party' becomes 'do' (do is a kind of party).
'to get excited' becomes 'rouse' (to rouse someone is to excite them).
'endlessly' means to remove the last letter.
'rouse' with its last letter taken away is 'rous'.
'o'+'do'+'rous'='ODOROUS'
(Other definitions for odorous that I've seen before include "Aromatic" , "Smelly" , "Giving off a smell" , "Scented" , "having a distinct aroma" .)