A battle sense turned into knowledge (9)
I believe the answer is:
awareness
'knowledge' is the definition.
(I know that awareness is a type of knowledge)
'a battle sense turned' is the wordplay.
'battle' becomes 'war' (I've seen this in other clues).
'turned' is an anagram indicator.
'sense' is an anagram of 'eness'.
'a'+'war'+'eness'='AWARENESS'
'into' acts as a link.
(Other definitions for awareness that I've seen before include "Insight" , "Grasp" , "Consciousness, knowingness" , "Knowledge (of a fact)" , "Knowing" .)