Off course without hard drug disposal unit? (3,4)

I believe the answer is:

ash tray

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'drug disposal unit?' is the definition.
I don't know anything about this answer so I can't tell whether this works.

'off course without hard' is the wordplay.
'off course' becomes 'astray' (to be led astray is to be led off course).
'without' is an insertion indicator ('without' can be similar in meaning to 'outside').
'hard' becomes 'h' (abbreviation used in pencil classifications).
'astray' going around 'h' is 'ASH-TRAY'.

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I've seen this clue in the Sydney Morning Herald.

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