A dark time for the champion, we hear (5)
I believe the answer is:
night
'a dark time' is the definition.
(I've seen this before)
'champion we hear' is the wordplay.
'champion' becomes 'knight' (I have seen 'Heroic champion' mean 'knight' so perhaps 'champion' could also mean 'knight').
'we hear' shows a homophone (sound like).
'knight' sounds like 'NIGHT'.
'for the' acts as a link.
(Other definitions for night that I've seen before include "late" , "Time for turning" , "8d [DARKNESS]" , "Period of darkness" , "Evening" .)