Crossword Genius

Most difficult dart he's thrown (7)

Ross

I believe the answer is:

hardest

'most difficult' is the definition.
('hard' can be a synonym of 'difficult')

'dart he's thrown' is the wordplay.
'thrown' indicates anagramming the letters.
'dart'+'hes'='darthes'
'darthes' with letters rearranged gives 'HARDEST'.

(Other definitions for hardest that I've seen before include "Most difficult or firm" , "Trashed (anag) - most oppressive" , "Red hats (anag.)" , "most difficult to unravel" .)

I've seen this clue in The Telegraph.
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