Preacher's spoken, boring Scrooge (9)
I believe the answer is:
moraliser
'preacher's' is the definition.
(I've seen this before)
'spoken boring scrooge' is the wordplay.
'spoken' becomes 'oral' (similar in meaning).
'boring' means one lot of letters goes inside another (to bore something can mean to drill into it).
'scrooge' becomes 'miser' (Dickens' Ebenezer Scrooge is a miser).
'oral' inserted within 'miser' is 'MORALISER'.
(Other definitions for moraliser that I've seen before include "preacher" , "Ethical speaker" .)