Car in showroom in Islington (4)
I believe the answer is:
mini
'car' is the definition.
(Mini Cooper)
'in showroom in islington' is the wordplay.
'in' indicates the answer is hidden within the clue.
'MINI' can be found hidden inside 'showroom in islington'.
(Other definitions for mini that I've seen before include "Baby" , "Cult British car" , "type of garment" , "Short skirt - small car" , "Car designed by Issigonis" .)