In Berlin expect a row (4)
I believe the answer is:
line
'row' is the definition.
(as in a row of things)
'in berlin expect a' is the wordplay.
'in' indicates a hidden word.
'LINE' is hidden within 'berlin expect a'.
(Other definitions for line that I've seen before include "job" , "classified information" , "A length without breadth or thickness" , "Row - occupation" , "Wrinkle; row" .)