Capital tour, lastly to coral island (7)
I believe the answer is:
tripoli
'capital' is the definition.
(capital of Libya)
'tour lastly to coral island' is the wordplay.
'tour' becomes 'trip' (I've seen this in another clue).
'lastly' indicates one should take the final letters.
'island' becomes 'i' (geographical abbreviation).
The last letters of 'to coral' are 'ol'.
'trip'+'ol'+'i'='TRIPOLI'
(Other definitions for tripoli that I've seen before include "North African capital" , "city on the Mediterranean" , "Libyan capital" , "Middle East port" , "where there's been regime change" .)