Acerbic criminal nattering about closure of banks (10)
I believe the answer is:
astringent
'acerbic' is the definition.
(synonyms)
'criminal nattering about closure of banks' is the wordplay.
'criminal' indicates an anagram.
'about' indicates putting letters inside.
'closure of' indicates one should take the final letters.
The final letter of 'banks' is 's'.
'nattering' anagrammed gives 'atringent'.
'atringent' going around 's' is 'ASTRINGENT'.
(Other definitions for astringent that I've seen before include "(Of taste) sharp, bitter" , "Lotion" , "Caustic" , "piercing" , "Sharp or severe in manner" .)