Years possibly follow as a metal-tester (7)
I believe the answer is:
assayer
'tester' is the definition.
(I have seen 'Tester of metals ' mean 'assayer' so perhaps 'tester' could also mean 'assayer')
'years possibly follow as' is the wordplay.
'possibly' is an anagram indicator.
'follow' is a charade indicator (letters next to each other).
'years' anagrammed gives 'sayer'.
'sayer' after 'as' is 'ASSAYER'.
'a metal' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for assayer that I've seen before include "One does chemical tests on metals" , "Inspector" , "One analyses metals" , "Tester of metals" , "Tester of chemicals on metal" .)