Military help broadcast position (3,5)

I believe the answer is:

air cover

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'military help' is the definition.
(support provided by aircraft)

'broadcast position' is the wordplay.
'broadcast' becomes 'air' (synonyms).
'position' becomes 'cover' (I can't explain this - if you can you should believe this answer much more).
'air'+'cover'='AIR COVER'

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(Other definitions for air cover that I've seen before include "Protection given by planes" , "support of planes" , "Planes giving protection" .)

I've seen this clue in The Independent.

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