Puts an end to saintly operations (5)
I believe the answer is:
'puts an end to' is the definition.
(I've seen this in another clue)
'saintly operations' is the wordplay.
'saintly' becomes 'st' (I can't explain this - if you can you should believe this answer much more).
'operations' becomes 'ops' (abbreviation).
'st'+'ops'='STOPS'
Can you help me to learn more?
(Other definitions for stops that I've seen before include "Prevents" , "Halts" , "Posts (anag.)" , "Checks" , "Ceases" .)