1D derived from core properties of elder, horseradish, rue and fenugreek (4)
I believe the answer is:
drug
'core properties of elder horseradish rue and fenugreek' is the definition.
I can't tell whether this defines the answer.
'1d derived' is the wordplay.
'rd' becomes 'd'.
'derived' becomes 'rug' (I can't justify this - if you can you should believe this answer much more).
'd'+'rug'='DRUG'
'from' acts as a link.
Can you help me to learn more?
(Other definitions for drug that I've seen before include "Item of medicine or a narcotic" , "Pharmaceutical (or recreational) item" , "Perhaps grass" , "Substance used in medicine, often abused" , "Form of medicine" .)