Protector (8)
'protector' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for guardian that I've seen before include "Curator" , "One in loco parentis" , "Defender, protector" , "Caretaker" , "Protector or watchful angel" .)
(Other definitions for surge that I've seen before include "Sudden forward movement" , "Increase rapidly in intensity" , "Sudden uprush" , "Rapid increase; powerful movement" , "Well up" .)