Green, not unusual (6)
I believe the answer is:
common
I believe this is a double definition.
'green' is the first definition.
('common' can be a synonym of 'green')
'not unusual' is the second definition.
(Other definitions for common that I've seen before include "Widespread, prevalent" , "Average, ordinary or usual" , "Without special distinction, ordinary" , "Vulgar or frequent" , "Ten a penny" .)