Journalist on leave finally in New York cab (7)
I believe the answer is:
hackney
'cab' is the definition.
(type of horse-drawn carriage)
'journalist on leave finally in new york' is the wordplay.
'journalist' becomes 'hack' (I've seen this in other clues).
'on' is a charade indicator (letters next to each other).
'finally' says to take the final letters.
'in' is an insertion indicator.
'new york' becomes 'ny'.
The final letter of 'leave' is 'e'.
'e' inserted within 'ny' is 'ney'.
'hack'+'ney'='HACKNEY'
(Other definitions for hackney that I've seen before include "Old cab - London borough" , "Carriage for hire" , "Wear out" , "district of London" , "A kind of taxi or car for hire" .)