Doctor protects a bystander (9)
I believe the answer is:
spectator
'bystander' is the definition.
(thesaurus)
'doctor protects a' is the wordplay.
'doctor' indicates anagramming the letters.
'protects'+'a'='protectsa'
'protectsa' with letters rearranged gives 'SPECTATOR'.
(Other definitions for spectator that I've seen before include "weekly magazine?" , "I attend sporting event" , "member of the crowd" , "weekly publication" , "Person watching" .)