Exclusive small shop (5)
I believe the answer is:
scoop
'exclusive' is the definition.
(as in a newspaper scoop)
'small shop' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'shop' becomes 'coop' (short for The Co-operative Group).
's'+'coop'='SCOOP'
(Other definitions for scoop that I've seen before include "Exclusive report" , "Press exclusive" , "Exclusive news item" , "Ice-cream utensil" , "Dig out - story that makes the headlines" .)