Deliver a sermon, say (6)
(Other definitions for preach that I've seen before include "A perch (anag.)" , "Pontificate" , "Lecture" , "Sermonise" , "Publicly proclaim" .)
(Other definitions for orate that I've seen before include "Talk pompously" , "Speechify" , "Speaker may" , "Make a flowery speech" , "Pontificate" .)