Hubble-bubble (6)
I believe the answer is:
hookah
'hubble-bubble' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for hookah that I've seen before include "Smoking pipe, using water" , "Oriental water pipe for smoking" , "Pipe for smoking marijuana etc" , "A pipe; sounds like a rugby position" , "Sort of pipe" .)