Dismiss with a curt exclamation about wicked sin (6)
I believe the answer is:
'dismiss' is the definition.
'a curt exclamation about wicked sin' is the wordplay.
'a curt exclamation' becomes 'bah' (I am not sure about the 'curt' bit.).
'about' is an insertion indicator.
'wicked' is an anagram indicator.
'sin' is an anagram of 'nis'.
'bah' placed around 'nis' is 'BANISH'.
'with' is the link.
Can you help me to learn more?
(Other definitions for banish that I've seen before include "Condemn to exile", "Expel from a community or group", "Send (someone) away", "Expel or expatriate", "Throw out".)