The most common and most likely answer to this crossword clue is the 4 letter word HEMP
I've seen this crossword clue in The Times
H
E
M
P
More clues leading to the result HEMP
- Borderline soft drug
- Parking on the edge? Hash is made of it
- Border patroller's opening drug
- Drug supplied by ambassador meeting politician
- Cannabis and ecstasy in prison
- Border on soft fibre
- Cannabis grown by extremely hirsute politician
- Pot plant planted initially on border
- Part of garment with soft fibre
- The male politician offering ropy stuff
Buddy explains!

The straight part
We know that "Drug" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case drug = hemp.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does HEMP mean?
HEMP noun- A tall annual herb, Cannabis sativa, native to Asia.
- Various products of this plant, including fibres and the drug cannabis.