Affect with drug, producing odd reaction laced with sulphur (9)
I believe the answer is:
narcotise
'affect with drug' is the definition.
I can't judge whether this definition defines the answer.
'odd reaction laced with sulphur' is the wordplay.
'odd' indicates an anagram.
'laced with' means one lot of letters goes inside another (I've seen this in other clues).
'sulphur' becomes 'S' (synonyms).
'reaction' is an anagram of 'narcotie'.
'narcotie' going around 's' is 'NARCOTISE'.
'producing' is the link.
Can you help me to learn more?
(Other definitions for narcotise that I've seen before include "Numb" , "administer drug" , "put under influence of drugs" .)