Resolute business concern (4)
I believe the answer is:
firm
I believe this clue is a triple definition!
'resolute' is the first definition.
(similar in meaning)
'business' is the second definition.
(firm is a kind of business)
'concern' is the third definition.
(I know that firm is a type of concern)
(Other definitions for firm that I've seen before include "team of doctors in hospital" , "Stable; business" , "team of doctors and assistants" , "Solid - business" , "Company - stable" .)