Gold casket marked and scored (12)
I believe the answer is:
orchestrated
'scored' is the definition.
(orchestrating is a kind of scoring)
'gold casket marked' is the wordplay.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'casket' becomes 'chest'.
'marked' becomes 'rated'.
'or'+'chest'+'rated'='ORCHESTRATED'
'and' acts as a link.
(Other definitions for orchestrated that I've seen before include "Musically arranged" , "presented?" , "Organised" .)