Rap battle's conclusion after fine dance includes spot of filth (9)
I believe the answer is:
freestyle
'rap' is the definition.
The definition and answer can be both related to natural events as well as being singular nouns.
Maybe you can see an association between them that I can't see?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for freestyle that I've seen before include "Race with few restrictions on technique" , "no-holds-barred event" , "any kind you like" , "Race where swimmers can choose what stroke to use" , "Crawl, usually" .)