Current Theme: Crosswordese
ARETE /uh.RET/ n. a sharp narrow mountain ridge

Another thing crossword constructors like to do, by the way, is use secondary, less expected, meanings of words. In this case, ARETE might also refer to an old Greek word that related to ‘virtue’ (‘knowledge’ being the ultimate), and was often bound up in the context of ‘achieving your very best’. That’s why you’ll occasionally see clues for this word like [Sum of one's virtues, to the Greek] or [Virtue to Aristotle].
It’s a trap for beginners, but it won’t snare you ;-)
Actually, in the Greek context, ARETE is pronounced differently to the ‘mountain ridge’. Puzzle makers don’t worry about pronunciations in their clues, though. Probably because that would take a lot of the fun out of it for them!
For the Scrabble players, today’s word makes a nice alternative play to the rather mundane EATER.
P.S. I might make an occasional habit of tucking away Collins- (CSW-) only words in a footnote so North American Scrabblers can safely avoid them. In today’s case, here’s the footnote…
Collins allows another obscure anagram of ARETE, namely REATE#, which is a type of plant often more casually referred to as the ‘Water-crowfoot’.