Some use elementary uprising for fights (6)
I believe the answer is:
melees
'for fights' is the definition.
(I've seen this in another clue)
'some use elementary uprising' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'uprising' says the letters should be written backwards.
'seelem' is hidden within 'use elementary'.
'seelem' back-to-front is 'MELEES'.
(Other definitions for melees that I've seen before include "Scrimmages, free-for-alls" , "Noisy and confused fights" , "breaches of the peace" , "Noisy disorganised fights" .)