Some upstanding militiamen ended purge (5)
I believe the answer is:
enema
'purge' is the definition.
(thesaurus)
'some upstanding militiamen ended' is the wordplay.
'upstanding' says the letters should be written in reverse.
'some' indicates a hidden word (some of the parts of the word are used).
'amene' is hidden within 'militiamen ended'.
'amene' backwards is 'ENEMA'.
(Other definitions for enema that I've seen before include "medicine to get you going" , "Medical liquid introduced anally" , "Fluid injected rectally" , "Suppository" , "Procedure for vacating the bowels" .)