Business practice? (6)
I believe the answer is:
custom
This clue is a double definition.
'business' is the first definition.
(custom is a kind of business)
'practice?' is the second definition.
(custom is a kind of practice)
(Other definitions for custom that I've seen before include "''Age cannot wither her, nor ... stale (Antony and Cleopatra)" , "Way of doing things" , "'Habit, practice (6)'" , "Established usage" , "Regular process" .)