Expedition initially seeking a distant island (6)
I believe the answer is:
safari
'expedition' is the definition.
(safari is a kind of expedition)
'initially seeking a distant island' is the wordplay.
'initially' says to take the initial letters.
'a distant' becomes 'afar' (I've seen this before).
'island' becomes 'i'.
The first letter of 'seeking' is 's'.
's'+'afar'+'i'='SAFARI'
(Other definitions for safari that I've seen before include "African hunting expeiditon" , "North African capital" , "Hunting trip" , "Big game expedition" , "Hunting expedition (in Africa)" .)