Painful experience in gold trade (6)
I believe the answer is:
ordeal
'painful experience' is the definition.
(I've seen this before)
'gold trade' is the wordplay.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'trade' becomes 'deal' (synonyms).
'or'+'deal'='ORDEAL'
'in' acts as a link.
(Other definitions for ordeal that I've seen before include "Prolonged suffering, difficult to endure" , "Long painful experience" , "very hard test" , "A tough time or hardship" , "Tough test in Laredo" .)