Rising island in the Atlantic (9)
I believe the answer is:
ascension
This could be a double definition.
'rising' is the first definition.
(thesaurus)
'island in the atlantic' is the second definition.
'ascension' can be an answer for 'island' (I've seen this before). I'm not certain of the 'in the atlantic' bit.
Can you help me to learn more?
(Other definitions for ascension that I've seen before include "Island in the South Atlantic" , "religious feast" , "A movement upward" , "distance in hours measured by this, right?" , "Canonises on Christ's way to heaven" .)