In street unending party getting louder and louder (9)
I believe the answer is:
crescendo
'in' is the definition.
Both the definition and answer are adjectives. Maybe there's a link between them I don't understand?
'street unending party getting louder and louder' is the wordplay.
I cannot quite see how this works, but
'party' could be 'do' (do is a kind of party) and 'do' is found within the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for crescendo that I've seen before include "Building up of sound" , "Gradually increasing in volume" , "Conceders (anag.)" , "increase in sound level" , "Rising noise" .)