Athenian's way of working in metal (5)
I believe the answer is:
timon
'athenian's' is the definition.
(I've seen this before)
'way of working in metal' is the wordplay.
'way of working' becomes 'mo' (I've seen this in other clues).
'in' indicates putting letters inside.
'metal' becomes 'tin' (tin is a kind of metal).
'mo' going inside 'tin' is 'TIMON'.
(Other definitions for timon that I've seen before include "Athenian in Shakespeare play" , "legendary misanthrope" , "part of Shakespeare" , "Shakespeare's Athenian" , "Shakespearean Athenian" .)