Oil change after journey in African port (7)
I believe the answer is:
tripoli
'african port' is the definition.
(I've seen this in another clue)
'oil change after journey' is the wordplay.
'change' indicates an anagram.
'after' means one lot of letters go next to another.
'journey' becomes 'trip' (trip is a kind of journey).
'oil' with letters rearranged gives 'oli'.
'oli' put after 'trip' is 'TRIPOLI'.
'in' acts as a link.
(Other definitions for tripoli that I've seen before include "North African capital" , "powdery deposit" , "Polish" , "Libya's capital" , "Capital of Libya" .)