God who wields Mjolnir (4)
I believe the answer is:
thor
'god who wields mjolnir' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for thor that I've seen before include "Divine figure" , "Germanic thunder god; early US IRBM" , "can be classed as immortal" , "Norse god of war" , "Imitative artistic work" .)