Island hostile to another island miles away (7)
I believe the answer is:
antigua
'island' is the definition.
(I've seen this before)
'hostile to another island miles away' is the wordplay.
'hostile to' becomes 'anti' (anti means hostile to or opposed to).
'another island miles' becomes 'gu' (I can't explain this - if you can you should give a lot more credence to this answer).
'away' becomes 'A' (abbreviation as used in sports fixtures).
'anti'+'gu'+'a'='ANTIGUA'
Can you help me to learn more?
(Other definitions for antigua that I've seen before include "Largest of Leeward Is." , "One of the Leeward Islands" , "West Indies island" , "warm island" , "former British possession" .)