Half the battle is getting it the heading (5)
I believe the answer is:
title
'the heading' is the definition.
(title is a kind of heading)
'half the battle is getting it' is the wordplay.
'half the' suggests halving the letters.
'is getting' says to put letters next to each other.
'it' becomes 'ti' (I can't explain this - if you can you should believe this answer much more).
'battle' cut in half is 'tle'.
'tle' after 'ti' is 'TITLE'.
Can you help me to learn more?
(Other definitions for title that I've seen before include "Mr or Mrs, say" , "inscription" , "Lord, sir, doctor etc." , "Appellation of rank" , "Name of book, picture or rank" .)