Finest (6)
'finest' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for best that I've seen before include "George -, footballer" , "Peerless" , "Most excellent - late football star" , "Supreme" , "Of the highest quality" .)
(Other definitions for nicest that I've seen before include "Most pleasant or fine" , "Most agreeable" , "Insect (anag)" , "Most attractive" , "most appetising" .)