Test gold before transaction (6)
I believe the answer is:
ordeal
'test' is the definition.
(thesaurus)
'gold before transaction' is the wordplay.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'before' is a charade indicator (letters next to each other).
'transaction' becomes 'deal' (deal is a kind of transaction).
'or'+'deal'='ORDEAL'
(Other definitions for ordeal that I've seen before include "A difficult and harrowing experience" , "A difficult or harrowing time" , "Difficult and testing experience" , "Long painful experience" , "Loader (anag.)" .)