Preacher to lapse explosively (7)
I believe the answer is:
apostle
'preacher' is the definition.
(the apostles spread Jesus' message)
'to lapse explosively' is the wordplay.
'explosively' indicates anagramming the letters.
'to'+'lapse'='tolapse'
'tolapse' is an anagram of 'APOSTLE'.
(Other definitions for apostle that I've seen before include "One of the biblical twelve (7)well don" , "Leaps to find religious follower" , "Ardent espouser of new system" , "Maybe Peter" , "Good man" .)