Keep breaking pots (4)
I believe the answer is:
stop
'keep' is the definition.
(I know that stop is a more specific form of the action defend)
'breaking pots' is the wordplay.
'breaking' indicates an anagram.
'pots' anagrammed gives 'STOP'.
(Other definitions for stop that I've seen before include "high card in bridge" , "Red light signal" , "Refrain from" , "Finished" , "break" .)