Jack retained by car manufacturer — it's common in Norway (5)
I believe the answer is:
fjord
'it's common in norway' is the definition.
'jack retained by car manufacturer' is the wordplay.
'jack' becomes 'j' (playing card abbreviation).
'retained by' indicates putting letters inside.
'car manufacturer' becomes 'ford'.
'j' placed inside 'ford' is 'FJORD'.
(Other definitions for fjord that I've seen before include "Norwegian inlet (J, not I)" , "part of Norway" , "Northern location?" , "Rock-bound inlet" , "Rocky inlet" .)