Direst sort of tread (6)
I believe the answer is:
stride
'tread' is the definition.
(I know that tread can be written as stride)
'direst sort' is the wordplay.
'sort' indicates an anagram.
'direst' is an anagram of 'STRIDE'.
'of' is the link.
(Other definitions for stride that I've seen before include "Extended footstep" , "style of jazz piano" , "use your legs!" , "Move with long steps" , "march" .)