A contradiction in terms, but good! (9)
I believe the answer is:
wholesome
'good' is the definition.
(thesaurus)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for wholesome that I've seen before include "Beneficial" , "Healthy in body, taste or morals" , "Previously propitious" , "Good for you!" , "Moral" .)