Stylish clothes, ultimately, dyer’s transformed (6)
I believe the answer is:
dressy
'stylish' is the definition.
(in formal dress)
'clothes ultimately dyer's transformed' is the wordplay.
'ultimately' suggests the final letters.
'transformed' indicates anagramming the letters.
The final letter of 'clothes' is 's'.
's'+'dyers'='sdyers'
'sdyers' is an anagram of 'DRESSY'.
(Other definitions for dressy that I've seen before include "Stylish with regard to clothes" , "(Of clothes) smart, formal" , "Sartorially elegant" , "Liking to wear fancy or formal clothes" , "Smartly clad, wearing stylish clothes" .)