It's half the battle getting the others in to give support (7)
I believe the answer is:
trestle
'support' is the definition.
(I've seen this before)
'it's half the battle getting the others' is the wordplay.
'it's half the' means to take half the letters.
'getting' indicates putting letters inside.
'the others' becomes 'rest' (I've seen this before).
'battle' cut in half is 'tle'.
'tle' going around 'rest' is 'TRESTLE'.
'in to give' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for trestle that I've seen before include "Letters (anag) - table" , "Letters about a table support" , "Frame to hold table" , "Framework to support a flat surface -- letters (anag)" , "support for board" .)