Jack goes in car to find Scandinavian inlet (5)
I believe the answer is:
fjord
'scandinavian inlet' is the definition.
(I've seen this in another clue)
'jack goes in car' is the wordplay.
'jack' becomes 'J' (playing card abbreviation).
'goes in' is an insertion indicator.
'car' becomes 'ford' (Ford is a make of car).
'j' inserted within 'ford' is 'FJORD'.
'to find' is the link.
(Other definitions for fjord that I've seen before include "Norwegian inlet (J, not I)" , "Sea inlet" , "Rocky inlet" , "Long narrow inlet" , "Northern location?" .)