Being in neutral territory will make all the difference (5)

I believe the answer is:

alter

I'm a little stuck... Click here to teach me more about this clue!

'all the difference' is the definition.
I can't tell whether this definition defines the answer.

'being in neutral territory will' is the wordplay.
'being in' says the answer is hidden in the clue.
'ALTER' can be found hidden inside 'neutral territory will'.

'make' acts as a link.

Can you help me to learn more?

(Other definitions for alter that I've seen before include "Bout of extravagant spending" , "Alert to change" , "Vary" , "Make changes to" , "Adapt" .)

I've seen this clue in the Evening Standard.

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