Those starting on good religious evangelists seem monsters (5)
I believe the answer is:
ogres
'monsters' is the definition.
(ogre is a type of monster)
'those starting on good religious evangelists seem' is the wordplay.
'those starting' says to take the initial letters (the letters which start the words).
The initial letters of 'on good religious evangelists seem' is 'OGRES'.
(Other definitions for ogres that I've seen before include "Monsters can be goers" , "Awful brutes" , "Monstrous giants and man-eaters" , "Giants in fairytales" , "Fairytale giants" .)