One true sort is on the way (2,5)
I believe the answer is:
en route
'on the way' is the definition.
(synonyms)
'one true sort' is the wordplay.
'sort' indicates anagramming the letters.
'one'+'true'='onetrue'
'onetrue' anagrammed gives 'EN ROUTE'.
'is' acts as a link.
(Other definitions for en route that I've seen before include "On the way - in France" , "Along the way" , "'On the way (2,5)'" , "As part of a journey" , "March" .)