So long in Madrid? (5)

I believe the answer is:

adios

'so long in madrid?' is the definition.
('goodbye' or 'so long' in Spanish)

This is the entire clue.

(Other definitions for adios that I've seen before include "Spanish farewell" , "Goodbye to Spain" , "Goodbye, senor" , "Bye-bye (amigo)" , "so long in Mexico" .)

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app