Way of working in ink transformed old robe (6)
I believe the answer is:
kimono
'robe' is the definition.
(kimono is a kind of robe)
'way of working in ink transformed old' is the wordplay.
'way of working' becomes 'mo' (I've seen this in other clues).
'in' is an insertion indicator.
'transformed' indicates an anagram.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'ink' with letters rearranged gives 'kin'.
'mo' put within 'kin' is 'kimon'.
'kimon'+'o'='KIMONO'
(Other definitions for kimono that I've seen before include "dressing-gown" , "wrapper" , "Long loose Japanese robe" , "Japanese loose, sashed garment" , "Asian garment" .)