Drink for pirate travelling to island on top of flagship (8)
I believe the answer is:
aperitif
'drink' is the definition.
(aperitif is a kind of drink)
'pirate travelling to island on top of flagship' is the wordplay.
'travelling' indicates an anagram.
'to island' becomes 'i' (geographical abbreviation).
'on top of' says to take the initial letters.
The initial letter of 'flagship' is 'f'.
'pirate' is an anagram of 'aperit'.
'aperit'+'i'+'f'='APERITIF'
'for' is the link.
(Other definitions for aperitif that I've seen before include "If pirate may have a drink before dinner?" , "alcohol before meal" , "Alcoholic drink before a meal, like sherry" , "Alcoholic beverage as an appetiser" , "Pre-nosh tipple?" .)