Smoking habit? (6)

I believe the answer is:

reefer

I believe this is a double definition.

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

'habit?' is the second definition.
(I've seen this before)

(Other definitions for reefer that I've seen before include "Midshipman (sl.)" , "Cigarette containing cannabis - jacket" , "roll of hemp" , "habit?" , "A wool jacket; a spliff" .)

I've seen this clue in The Sun.

Want a hint initially instead of a full solution? Install my app