Island possibly giving us energy (8)
I believe the answer is:
guernsey
'island' is the definition.
(I've seen this before)
'possibly giving us energy' is the wordplay.
'possibly' indicates an anagram.
'giving' means one lot of letters go next to another.
'us' put next to 'energy' is 'usenergy'.
'usenergy' is an anagram of 'GUERNSEY'.
(Other definitions for guernsey that I've seen before include "Lyric poem" , "Second largest Channel Island" , "Second-largest Channel Island" , "Sir Walter Scott novel" , "One of the Channel Islands" .)