Try drugs at last, I’m afraid (4)
I believe the answer is:
seek
'try' is the definition.
(I know that try can be written as seek)
'drugs at last i'm afraid' is the wordplay.
'at last' indicates one should take the final letters.
'i'm afraid' becomes 'eek' (expression of fear).
The final letter of 'drugs' is 's'.
's'+'eek'='SEEK'
(Other definitions for seek that I've seen before include "'. . . . and ye shall find'" , "Hunt, look for" , "Go looking for" , "Attempt to find; ask for" , "Try to locate or reach" .)