They dispense with revolutionary brumes (8)
I believe the answer is:
chemists
'they dispense' is the definition.
The definition suggests an adverb but the answer is not.
'with revolutionary brumes' is the wordplay.
'with' says to put letters next to each other.
'revolutionary' becomes 'Che' (Che Guevara the Marxist revolutionary).
'brumes' becomes 'mists' (I can't justify this - if you can you should believe this answer much more).
'che' next to 'mists' is 'CHEMISTS'.
Can you help me to learn more?
(Other definitions for chemists that I've seen before include "pair of Boots?" , "They dispense prescriptions" , "Scientists" , "Pharmacists, say" , "Drug dealers" .)