Chum protecting journalist, one to act as a go-between (7)
I believe the answer is:
mediate
'act as a go-between' is the definition.
(I've seen this before)
'chum protecting journalist one' is the wordplay.
'chum' becomes 'mate' (I've seen this before).
'protecting' indicates putting letters inside.
'journalist' becomes 'ed' (short for editor).
'one' becomes 'i' (Roman numeral).
'ed'+'i'='edi'
'mate' enclosing 'edi' is 'MEDIATE'.
'to' is the link.
(Other definitions for mediate that I've seen before include "To referee" , "Act as negotiator or peacemaker" , "moderate" , "Act as intermediary" , "Act as negotiator between opposing side" .)