Oust with a disgusted utterance about terrible sin (6)
I believe the answer is:
banish
'oust' is the definition.
(thesaurus)
'disgusted utterance about terrible sin' is the wordplay.
'disgusted utterance' becomes 'bah' (I can't justify this - if you can you should give a lot more credence to this answer).
'about' indicates putting letters inside.
'terrible' indicates an anagram.
'sin' with letters rearranged gives 'nis'.
'bah' placed around 'nis' is 'BANISH'.
'with a' is the link.
Can you help me to learn more?
(Other definitions for banish that I've seen before include "Cast out, ostracize" , "Exile (someone)" , "Send (someone) away" , "Send into exile" , "Drive away, maybe from country" .)