Cleans off weapons (6)
I believe the answer is:
lances
'weapons' is the definition.
(lance is a kind of weapon)
'cleans off' is the wordplay.
'off' is an anagram indicator.
'cleans' with letters rearranged gives 'LANCES'.
(Other definitions for lances that I've seen before include "Spears for horse soldiers" , "Spears for cavalrymen" , "Long pointed weapons" .)