Go-between using communication channels, politician falling short (8)
I believe the answer is:
mediator
'go-between' is the definition.
(I've seen this before)
'communication channels politician falling short' is the wordplay.
'communication channels' becomes 'media' (I've seen this before).
'politician' becomes 'tory' (I've seen this before).
'falling short' means to remove the last letter.
'tory' with its final letter taken off is 'tor'.
'media'+'tor'='MEDIATOR'
'using' is the link.
(Other definitions for mediator that I've seen before include "Go-between, negotiator" , "One intervening to settle a dispute" , "Negotiator between opposing parties" , "An honest broker" , "Person working to settle disputes" .)