Ignorant girl fighting English (7)
I believe the answer is:
unaware
'ignorant' is the definition.
(I've seen this before)
'girl fighting english' is the wordplay.
'girl' becomes 'una' (girl's name).
'fighting' becomes 'war'.
'english' becomes 'e' (abbreviation).
'una'+'war'+'e'='UNAWARE'
(Other definitions for unaware that I've seen before include "Ignorant - unenlightened" , "Not conscious of what is going on" , "Uninformed" , "Not realising" , "In the dark" .)