What the Navy's for, as RAF were a disaster (3,7)

I believe the answer is:

sea warfare

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'what the navy's' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'as raf were a disaster' is the wordplay.
'disaster' indicates anagramming the letters.
'as'+'raf'+'were'+'a'='asrafwerea'
'asrafwerea' with letters rearranged gives 'SEA WARFARE'.

'for' acts as a link.

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I've seen this clue in The Independent.

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