Short street party is swell (9)
I believe the answer is:
crescendo
'is swell' is the definition.
(thesaurus)
'short street party' is the wordplay.
'short' means to remove the last letter.
'street' becomes 'crescent' (crescent-shaped street).
'party' becomes 'do' (do is a kind of party).
'crescent' with its last letter taken away is 'crescen'.
'crescen'+'do'='CRESCENDO'
(Other definitions for crescendo that I've seen before include "Increasing noise" , "Becoming louder in soccer den" , "(Of music) gradually increasing in loudness" , "Gradual increase in loudness, musically" , "Intensify" .)