Craftsman is one among the craftier sort (9)
I believe the answer is:
artificer
'craftsman' is the definition.
(I know that craftsman can be written as artificer)
'one among the craftier sort' is the wordplay.
'one' becomes 'I' (Roman numeral).
'among' is an insertion indicator.
'sort' indicates anagramming the letters.
'craftier' is an anagram of 'artifcer'.
'i' placed into 'artifcer' is 'ARTIFICER'.
'is' is the link.
(Other definitions for artificer that I've seen before include "Mechanic in the armed forces" , "Skilled worker" , "Skilled craftsman" , "Mechanic in the army or navy" , "Military mechanic" .)