Righteous anger after nation’s exported zero dyestuff (6)
I believe the answer is:
indigo
'dyestuff' is the definition.
(indigo is a kind of dyestuff)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for indigo that I've seen before include "supplier of blue stuff" , "type of dye" , "Blue dyestuff" , "Mood - (Duke Ellington)" , "Spectral colour" .)