Business concern unlikely to change (4)
I believe the answer is:
firm
'business concern' is the definition.
(firm is a kind of business concern)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for firm that I've seen before include "securely rooted" , "commercial partnership" , "Steady sort of business organisation" , "Constant - concern" , "Well-established - business" .)