Capital journey to oil production (7)
I believe the answer is:
tripoli
'capital' is the definition.
(capital of Libya)
'journey to oil production' is the wordplay.
'journey' becomes 'trip' (trip is a kind of journey).
'production' indicates anagramming the letters.
'oil' anagrammed gives 'oli'.
'trip'+'oli'='TRIPOLI'
(Other definitions for tripoli that I've seen before include "Polish" , "North African city" , "Capital of Libya" , "powdery deposit" , "North African capital" .)