Channel that's trustworthy, we hear (6)
I believe the answer is:
strait
'channel' is the definition.
(strait is a kind of channel)
'trustworthy we hear' is the wordplay.
'trustworthy' becomes 'straight'.
'we hear' shows a homophone (sound like).
'straight' sounds like 'STRAIT'.
'that's' acts as a link.
(Other definitions for strait that I've seen before include "Catch in a trap" , "Narrow sort of traits (6)" , "Inlet" , "Narrow passage joining two large areas of water" , "watery scene?" .)