Retailer did not start arrangement in studio (7)
I believe the answer is:
atelier
'studio' is the definition.
(atelier is a kind of studio)
'retailer did not start arrangement' is the wordplay.
'did not start' means to remove the first letter.
'arrangement' is an anagram indicator.
'retailer' with its initial letter removed is 'etailer'.
'etailer' anagrammed gives 'ATELIER'.
'in' acts as a link.
(Other definitions for atelier that I've seen before include "I relate to workshop used by artist" , "Designer's workshop" , "Artist's studio (French)" , "Artist's workshop, studio" , "Tie earl up in the artist's place" .)