The most common and most likely answer to this crossword clue is the 9 letter word DEPRAVITY
I've seen this crossword clue in Financial Times
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More clues leading to the result DEPRAVITY
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The straight part
We know that "moral turpitude" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case moral turpitude = depravity.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does DEPRAVITY mean?
DEPRAVITY noun- The state or condition of being depraved; moral debasement.
- A particular depraved act or trait.
- (Christian theology) Inborn corruption, entailing the belief that every facet of human nature has been polluted, defiled, and contaminated by sin.