One light put up in shop (4)
I believe the answer is:
deli
'in shop' is the definition.
(I've seen this before)
'one light put up' is the wordplay.
'one' becomes 'i' (Roman numeral).
'light' becomes 'led' (abbreviation for light emitting diode).
'put up' says the letters should be written in reverse.
'i'+'led'='iled'
'iled' written backwards gives 'DELI'.
(Other definitions for deli that I've seen before include "Shop selling processed food products" , "Shop with unusual foods" , "Fine foods shop" , "place to buy food" , "food outlet" .)