But: I have a question about "sinful":
For clue 20A, the answer and how it parses are clear.
But the six-letter word that means "sinful" in that clue strikes me as having a problem in the "substitution test". Meaning, can you find a phrase where substituting one word (the answer) for the other (sinful) maintains the same meaning?
Maybe in U.K. usage. But in U.S. usage one would accompany one with a different verb than with the other.
[Postscript: Sure enough, it appears in U.K. usage as indicating someone sinful (in a particular religion) or someone who had extramarital sex (in the past).]