Pure and visibly free from disease (8)
I believe the answer is:
spotless
'pure' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for spotless that I've seen before include "Absolutely pure, clean" , "Perfect" , "What unsuccessful twitchers do" , "Spic-and-span" , "Above reproach - perfectly clean" .)