Laser treatment for noblemen (5)
I believe the answer is:
earls
'noblemen' is the definition.
(earl is a kind of nobleman)
'laser treatment' is the wordplay.
'treatment' indicates an anagram (letters treated or processed differently).
'laser' with letters rearranged gives 'EARLS'.
'for' is the link.
(Other definitions for earls that I've seen before include "counts" , "Laser the British peers" , "members of the House of Lords" , "Peers of the realm" , "They're below marquess and above viscount" .)