Sort mail out for preacher (8)
I believe the answer is:
moralist
'preacher' is the definition.
(I've seen this before)
'sort mail out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'sort'+'mail'='sortmail'
'sortmail' with letters rearranged gives 'MORALIST'.
'for' acts as a link.
(Other definitions for moralist that I've seen before include "principled person" , "Person of principle" , "Ail storm (anag)" , "Ethical figure" , "someone drawing lessons" .)