Sin makes adult leave Black Sea region (5)
I believe the answer is:
crime
'sin' is the definition.
(thesaurus)
'adult leave black sea region' is the wordplay.
'adult' becomes 'a' (abbreviation).
'leave' indicates named letters should be taken away.
'black sea region' becomes 'crimea' (I've seen this before).
'crimea' with 'a' removed is 'CRIME'.
'makes' is the link.
(Other definitions for crime that I've seen before include "Dangerous driving perhaps" , "they say it doesn't pay" , "Legal offence" , "Transgression of the law" , "Killing, for example" .)