Thought about islands being badly treated (7)
I believe the answer is:
misused
'badly treated' is the definition.
(I've seen this before)
'thought about islands' is the wordplay.
'thought' becomes 'mused' (musing is a kind of thinking).
'about' means one lot of letters goes inside another.
'islands' becomes 'is' (i is an abbreviation for island).
'mused' going around 'is' is 'MISUSED'.
'being' is the link.
(Other definitions for misused that I've seen before include "polluted, perhaps?" , "Applied wrongly" , "Falsely employed" , "wasted?" , "Treated badly" .)