Improved PM began differently (7)

I believe the answer is:

amended

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'improved' is the definition.
('amend' can be a synonym of 'improve')

I don't understand how the remainder of the clue works.

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(Other definitions for amended that I've seen before include "Rectified" , "Correct, improve" , "Modified for the better" , "Put right" , "Made changes to correct" .)

I've seen this clue in The Daily Express.

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