Weapon a Parisian dropped being pierced (5)
I believe the answer is:
stung
'pierced' is the definition.
(stinging is a kind of piercing)
'weapon a parisian dropped' is the wordplay.
I cannot really see how this works, but
'a parisian' could be 'un' and 'un' is found in the answer.
This may be the basis of clue (or it may be nonsense).
'being' acts as a link.
Can you help me to learn more?
(Other definitions for stung that I've seen before include "Robbed" , "Punctured eg by wasp" , "Offended" , "Wounded (by bee/wasp)" , "Swindled (slang)" .)