Sycophants left South Island to someone from Aden (6)
I believe the answer is:
yemeni
'sycophants left south' is the definition.
I can't tell whether this defines the answer.
'island to someone from aden' is the wordplay.
'island' becomes 'i' (geographical abbreviation).
'to' means one lot of letters go next to another (I've seen this in other clues).
'someone from aden' becomes 'yemen' (I can't justify this - if you can you should give a lot more credence to this answer).
'i' put after 'yemen' is 'YEMENI'.
Can you help me to learn more?
(Other definitions for yemeni that I've seen before include "Native of, eg, Aden" , "from the Middle East" , "ME citizen" , "Person from Sana'a, say" , "Person from Aden perhaps" .)