Cross France or Germany (4)
I believe the answer is:
ford
'cross' is the definition.
(fording is a kind of crossing)
'france or germany' is the wordplay.
'france' becomes 'f'.
'germany' becomes 'd' (international vehicle registration code).
'f'+'or'+'d'='FORD'
(Other definitions for ford that I've seen before include "Ex-president" , "Place to cross river" , "Shallow place for river crossing" , "38th US president, Gerald" , "way for pedestrians" .)