Pure description of a double-blank domino (8)
I believe the answer is:
spotless
'pure' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for spotless that I've seen before include "Without a mark, completely clean" , "Spic-and-span" , "showing no sign of acne?" , "Above reproach - perfectly clean" , "Fully clean" .)