Middle channel (6)
I believe the answer is:
medium
I believe this clue is a double definition.
'middle' is the first definition.
('medium' can be a synonym of 'middle')
'channel' is the second definition.
(thesaurus)
(Other definitions for medium that I've seen before include "Person who conducts a siance" , "Conduit of communication" , "The middle between two extremes" , "Average kind of spiritualist" , "Average, mean" .)