Faulty CD — it isn't clear (8)
I believe the answer is:
distinct
'clear' is the definition.
(synonyms)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for distinct that I've seen before include "Quite different" , "Readily distinguishable" , "Discrete, clear-cut" , "Well-defined and clear" , "Clear and separate from others" .)