The girl in those "Berlin Days" (5)
I believe the answer is:
linda
'the girl' is the definition.
'in those berlin days' is the wordplay.
'in' indicates a hidden word.
'LINDA' is hidden in the letters of 'those berlin days'.
(Other definitions for linda that I've seen before include "lady" , "23 [LOVELACE]" , "Girl's name (I, not Y)" , "girl" , "-- Gray, 'Dallas' star" .)