Shops show work by the setter retrospectively (7)
I believe the answer is:
emporia
'shops' is the definition.
(I've seen this before)
'show work by the setter retrospectively' is the wordplay.
'show' becomes 'air' (both can mean broadcast).
'work' becomes 'op' (common abbreviation for 'opus').
'by' means one lot of letters go next to another.
'the setter' becomes 'me' (the person that set the crossword).
'retrospectively' is a reversal indicator.
'air'+'op'+'me'='airopme'
'airopme' backwards is 'EMPORIA'.
(Other definitions for emporia that I've seen before include "Large retail outlets" , "sales outlets" , "Large retail shops" , "Trading centres" , "I'm a rope (anag)" .)