Damn old box carrying drug (8)
I believe the answer is:
execrate
'damn' is the definition.
(I've seen this before)
'old box carrying drug' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'box' becomes 'crate' (crate is a kind of box).
'carrying' is a charade indicator (letters next to each other) (in a down clue, the bottom letters carry others).
'drug' becomes 'e' (E is another name for ecstasy).
'crate' after 'e' is 'ecrate'.
'ex'+'ecrate'='EXECRATE'
(Other definitions for execrate that I've seen before include "Harshly criticise" , "Curse" , "Inveigh against" , "Utter curses with erect axe" , "'Abhor, find repugnant (8)'" .)