Intransigent in business (4)
I believe the answer is:
firm
I believe this is a double definition.
'intransigent' is the first definition.
(thesaurus)
'business' is the second definition.
(firm is a kind of business)
'in' is the link.
(Other definitions for firm that I've seen before include "team of doctors and assistants" , "Steady commercial organisation?" , "Compact - company" , "Resolute; company" , "Solid; secure" .)