Criticise smokers' instrument (8)
I believe the answer is:
panpipes
'instrument' is the definition.
(I've seen this before)
'criticise smokers'' is the wordplay.
'criticise' becomes 'pan' (informal term meaning to criticise heavily).
'smokers'' becomes 'pipes' (I can't justify this - if you can you should believe this answer much more).
'pan'+'pipes'='PANPIPES'
Can you help me to learn more?
(Other definitions for panpipes that I've seen before include "Musical instrument made of reeds of different lengths" , "Folk instrument" , "Primitive wind instrument" , "Musical wind instrument - syrinx" , "Simple wind instrument" .)