Assignation in a country station (5)
I believe the answer is:
tryst
'assignation' is the definition.
(I've seen this before)
'in a country station' is the wordplay.
'in' says the answer is hidden in the clue.
'TRYST' can be found hidden inside 'country station'.
(Other definitions for tryst that I've seen before include "private appointment" , "Romantic meeting" , "Rendezvous with lover" , "Secret assignment" , "Lovers' appointment" .)