Rivals see me in fights (7)
I believe the answer is:
enemies
'rivals' is the definition.
(enemy is a kind of rival)
'see me in fights' is the wordplay.
'fights' indicates an anagram (I've seen 'fighting' mean this (I've seen this in other clues)).
'see'+'me'+'in'='seemein'
'seemein' anagrammed gives 'ENEMIES'.
(Other definitions for enemies that I've seen before include "Those we fight" , "Foes, hostile groups" , "Foes, adversaries" , "Foes, opponents" .)