Avenger with a hammer (4)
I believe the answer is:
thor
'avenger with a hammer' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for thor that I've seen before include "Norse hammer-wielding god" , "Son of Odin and Freya" , "Norse god for whom Thursday is named" , "Scandinavian thunder-god" , "Scandinavian god of thunder and the weather" .)