Men do business, but it's a trial (6)
I believe the answer is:
ordeal
'it's a trial' is the definition.
(thesaurus)
'men do business' is the wordplay.
'men' becomes 'or' (I've seen this in other clues).
'do business' becomes 'deal' (I've seen this before).
'or'+'deal'='ORDEAL'
'but' is the link.
(Other definitions for ordeal that I've seen before include "Disturbing experience" , "Prolonged distressing experience" , "Severe or trying experience" , "Tribulation" , "Unpleasant and prolonged experience" .)