Beat the counter-Reformation (7)
I believe the answer is:
'beat' is the definition.
(I know that beat can be written as trounce)
'counter-reformation' is the wordplay.
'reformation' indicates an anagram.
'counter' anagrammed gives 'TROUNCE'.
'the' acts as a link.
(Other definitions for trounce that I've seen before include "tank" , "Thrash" , "Thump" , "Beat heavily" , "Utterly defeat" .)