Foreign currency for rail travel (4)
I believe the answer is:
lira
'foreign currency' is the definition.
(I've seen this in another clue)
'rail travel' is the wordplay.
'travel' indicates anagramming the letters (I've seen 'travels' mean this).
'rail' anagrammed gives 'LIRA'.
'for' acts as a link.
(Other definitions for lira that I've seen before include "Monetary unit of Italy" , "Old unit of Italian money" , "old European capital" , "Former unit of money in Italy" , "Former Italian currency unit" .)