Island without a young animal (3)
I believe the answer is:
cub
'young animal' is the definition.
(I've seen this before)
'island without a' is the wordplay.
'island' becomes 'cuba' (Cuba is an example).
'without' indicates named letters should be taken away.
'cuba' with 'a' taken away is 'CUB'.
(Other definitions for cub that I've seen before include "Young of certain animals" , "Young bear or lion" , "A baby fox or bear" , "Youngster, trainee" , "cheeky youngster" .)