Border patroller's opening drug (4)

I believe the answer is:

hemp

'drug' is the definition.
(I've seen this before)

'border patroller's opening' is the wordplay.
'border' becomes 'hem' (I've seen this before).
'opening' says to take the initial letters.
The first letter of 'patrollers' is 'p'.
'hem'+'p'='HEMP'

(Other definitions for hemp that I've seen before include "Rope, cannabis, plant" , "Cannabis sativa" , "Plant fibre used to make rope" , "Rope-making fibre" , "Narcotic drug" .)

I've seen this clue in The Times.

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