Former copper's competent and easily forgiven (9)
I believe the answer is:
excusable
'easily forgiven' is the definition.
'former copper's competent' is the wordplay.
'former' becomes 'ex'.
'copper's' becomes 'cus' (chemical symbol).
'competent' becomes 'able' (similar in meaning).
'ex'+'cus'+'able'='EXCUSABLE'
'and' acts as a link.
(Other definitions for excusable that I've seen before include "Forgivable, pardonable" , "Justifiable" , "Not entirely to blame" .)