he cursed endlessly, unravelling with no less depravity - (13)

I believe the answer is:

lecherousness

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'depravity' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

'he cursed endlessly unravelling with no less' is the wordplay.
'endlessly' means to remove the last letter.
'unravelling with' is an anagram indicator.
'he'+'cursed'='hecursed'
'hecursed' with its final letter taken off is 'hecurse'.
'no'+'less'='noless'
'hecurse' anagrammed with 'noless' makes 'LECHEROUSNESS'.

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