Big clash between superior forces (3,6)

I believe the answer is:

air battle

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'superior forces' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'big clash' is the wordplay.
'big' becomes 'air' (I can't justify this - if you can you should believe this answer much more).
'clash' becomes 'battle' (I've seen this in another clue).
'air'+'battle'='AIR BATTLE'

'between' acts as a link.

Can you help me to learn more?

I've seen this clue in The Globe and Mail.

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