Descriptor of island population left abandoned (7)
I believe the answer is:
keyword
'descriptor' is the definition.
I can't tell whether this definition defines the answer.
'island population left abandoned' is the wordplay.
I cannot quite see how this works, but
'island' could be 'key' (key can mean an island or reef) and 'key' is present in the answer.
The remaining letters 'word' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'of' is the link.
Can you help me to learn more?
(Another definition for keyword that I've seen is " Descriptive term or clue".)