Journey wasted oil and Arab capital (7)
I believe the answer is:
tripoli
'arab capital' is the definition.
'Tripoli' can be an answer for 'capital' (capital of Libya). I'm not sure about the 'arab' bit.
'journey wasted oil' is the wordplay.
'journey' becomes 'trip' (trip is a kind of journey).
'wasted' indicates anagramming the letters.
'oil' anagrammed gives 'oli'.
'trip'+'oli'='TRIPOLI'
'and' is the link.
Can you help me to learn more?
(Other definitions for tripoli that I've seen before include "City in Libya - city in Lebanon" , "North African capital" , "Place in Libya" , "powdery deposit" , "Middle East port" .)