Car for an ex president (4)
I believe the answer is:
ford
This could be a double definition.
'car' is the first definition.
(Ford is a make of car)
'an ex president' is the second definition.
'ford' can be an answer for 'president' (Gerald Ford). I am not sure about the 'an ex' bit.
'for' is the link.
Can you help me to learn more?
(Other definitions for ford that I've seen before include "Car firm" , "Shallow place for river crossing" , "Place to cross river" , "Famous American of yesteryear" , "Shallow crossing point in river" .)