Smoking jacket? (6)
I believe the answer is:
reefer
This clue is a double definition.
'smoking' is the first definition.
(I've seen this before)
'jacket?' is the second definition.
(I've seen this before)
(Other definitions for reefer that I've seen before include "Unofficial smoking" , "Hand-rolled cigarette" , "Warm jacket - cannabis cigarette" , "Easy" , "Double-breasted jacket for a man" .)