He manages to clean a weapon (5)
I believe the answer is:
lance
'weapon' is the definition.
(lance is a kind of weapon)
'he manages to clean a' is the wordplay.
'clean' can be anagrammed to 'LANCE'.
But, I am not clear how the anagram is indicated.
Can you help me to learn more?
(Other definitions for lance that I've seen before include "One like pike" , "Horseman's long weapon" , "Surgical knife" , "corporal may have at the front" , "Spear for a horse-soldier" .)