Clue: First to admire Mr Aneurin Bevan, our revolutionary 5 reformer? (5)
Answer: OBAMA
Explanation: Definition: 5 reformer
Initial letters ('first to') of '**A**dmire **M**r **A**neurin **B**evan **O**ur' reversed ('revolutionary'), for the US President who championed what is now known as Obamacare, and which the Republicans are hell-bent to counter.