Become ally of Kuwait with the power to corrupt (4,2,4)

I believe the answer is:

take up with

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'become ally' is the definition.
I can't judge whether this definition defines the answer.

'kuwait with the power to corrupt' is the wordplay.
'with' means one lot of letters go next to another.
'power' becomes 'p' (symbol in physics).
'to corrupt' is an anagram indicator (a corrupted form).
'kuwait'+'the'+'p'='kuwaitthep'
'kuwaitthep' anagrammed gives 'TAKE UP WITH'.

'of' acts as a link.

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I've seen this clue in The Times.

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