Grasp a fighting European by the head (9)
I believe the answer is:
awareness
'grasp' is the definition.
(I've seen this before)
'a fighting european by the head' is the wordplay.
'fighting' becomes 'war'.
'european' becomes 'e' (abbreviation e.g. EU).
'by' is a charade indicator (letters next to each other).
'the head' becomes 'ness' (ness is a headland**).
'a'+'war'+'e'+'ness'='AWARENESS'
(Other definitions for awareness that I've seen before include "Consciousness, sentience" , "State of being conscious" , "Perception" , "Grasp" , "Knowledge (of a fact)" .)