Athenian character gets in some sort of metal (8)
I believe the answer is:
antimony
'sort of metal' is the definition.
'athenian character gets in some' is the wordplay.
'athenian character' becomes 'timon' (Timon of Athens).
'gets in' means one lot of letters goes inside another.
'some' becomes 'any' ('any' can be similar in meaning to 'some').
'timon' inserted into 'any' is 'ANTIMONY'.
(Other definitions for antimony that I've seen before include "Toxic metallic element used in semiconductors" , "My nation (anag) - metallic element" , "Semimetallic element" , "Brittle element" , "One element" .)