Lets us riot and fight (6)
I believe the answer is:
tussle
'fight' is the definition.
(tussling is a kind of fighting)
'lets us riot' is the wordplay.
'riot' indicates an anagram.
'lets'+'us'='letsus'
'letsus' anagrammed gives 'TUSSLE'.
'and' acts as a link.
(Other definitions for tussle that I've seen before include "Grapple" , "A struggle or conflict" , "Struggle or wrestling match" , "Wrestle, scuffle" , "Vigorous struggle or scuffle" .)