A heavy price for an island (5)
I believe the answer is:
atoll
'island' is the definition.
(I know that atoll is a type of island)
'a heavy price for an' is the wordplay.
'a heavy price' becomes 'toll' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'for' says to put letters next to each other (I've seen this in other clues).
'an' becomes 'a'.
'toll' after 'a' is 'ATOLL'.
Can you help me to learn more?
(Other definitions for atoll that I've seen before include "Ring of coral" , "Pacific coral island" , "Coral island surrounding a lagoon" , "Bikini for one" , "String of islands" .)