Weapon that makes passion go haywire (6,3)
I believe the answer is:
poison gas
'weapon that' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'passion go haywire' is the wordplay.
'haywire' indicates anagramming the letters.
'passion'+'go'='passiongo'
'passiongo' with letters rearranged gives 'POISON-GAS'.
'makes' acts as a link.
Can you help me to learn more?
(Other definitions for poison gas that I've seen before include "Such as chlorine" , "Eg, sarin or phosgene" .)