High-level conflict (6,7)

I believe the answer is:

aerial warfare

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'high-level conflict' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.

'level conflict' is the wordplay.
'level' becomes 'aerial' (I can't explain this - if you can you should give a lot more credence to this answer).
'conflict' becomes 'warfare' (warfare is engagement in war).
'aerial'+'warfare'='AERIAL WARFARE'

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