Battle traitor taking over in heroic narrative (8)
I believe the answer is:
saratoga
'battle' is the definition.
(Saratoga is an example)
'traitor taking over in heroic narrative' is the wordplay.
'traitor' becomes 'rat' (I've seen this before).
'taking' says to put letters next to each other.
'over' becomes 'o' (cricket abbreviation**).
'in' is an insertion indicator.
'heroic narrative' becomes 'saga' (I've seen this before).
'rat'+'o'='rato'
'rato' going into 'saga' is 'SARATOGA'.
(Other definitions for saratoga that I've seen before include "British defeat" , "Place of battle" , "O'Gara sat out the NY horse racing track" , "US battle site" , "Trunk" .)