Observer protects a cocktail (9)
I believe the answer is:
spectator
'observer' is the definition.
(I know that spectator is a type of observer)
'protects a cocktail' is the wordplay.
'cocktail' indicates anagramming the letters.
'protects'+'a'='protectsa'
'protectsa' anagrammed gives 'SPECTATOR'.
(Other definitions for spectator that I've seen before include "found on the terraces?" , "Watcher" , "Onlooker; magazine" , "He attends matches" , "I attend sporting event" .)