Tennis star, one with vices (6)
I believe the answer is:
sinner
'tennis star' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe you can see an association between them that I don't see?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for sinner that I've seen before include "Offender against moral law" , "One in error" , "Transgressor of the moral law" , "Person straying" , "One breaking divine law" .)