European city in Antwerp or Toulouse (5)
I believe the answer is:
porto
'european city' is the definition.
(city in Portugal)
'in antwerp or toulouse' is the wordplay.
'in' indicates a hidden word.
'PORTO' is hidden in the letters of 'antwerp or toulouse'.
(Other definitions for porto that I've seen before include "City on the Douro estuary" , "Portuguese wine city on the Douro" , "City port of Portugal" , "champion of Europe" , "City in NW Portugal (Portuguese spelling)" .)