*Arbiter (7)
'arbiter' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for referee that I've seen before include "Umpire; arbitrator" , "One who decides" , "Sports adjudicator" , "Judge" , "Official who ensures fair play" .)
(Other definitions for rattler that I've seen before include "Excellent example" , "North American pit viper" , "old crate" , "Dangerous snake" , "US snake (colloq.)" .)
'arbiter' is the definition.
(a judge arbitrates)
This is all the clue.
(Other definitions for judge that I've seen before include "Deem; arbiter" , "Assess" , "Arbitrator" , "Adjuicator" , "rule" .)