Single chap died protecting king awaiting trial (2,6)
I believe the answer is:
on remand
'awaiting trial' is the definition.
(in custody before a trial)
'single chap died protecting king' is the wordplay.
'single' becomes 'one' (a single thing - only one).
'chap' becomes 'man' (chap can mean a man).
'died' becomes 'd' (abbreviation next to the year of someone's death).
'protecting' is an insertion indicator (inserted letters are held or protected).
'king' becomes 'R' (abbreviation of Latin rex).
'one'+'man'+'d'='onemand'
'onemand' placed around 'r' is 'ON REMAND'.
(Other definitions for on remand that I've seen before include "Demon ran wild, being held in custody pending trial" , "awaiting court's decision?" , "officially not out" , "Having been sent back into custody" , "Awaiting trial" .)