Trial or trade (6)
I believe the answer is:
ordeal
'trial' is the definition.
(I've seen this before)
'or trade' is the wordplay.
'trade' becomes 'deal' (synonyms).
'or'+'deal'='ORDEAL'
(Other definitions for ordeal that I've seen before include "Severe or trying experience" , "Unpleasant and prolonged experience" , "Loader (anag.)" , "A difficult and harrowing experience" , "Long, unpleasant experience" .)