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' indicates putting letters inside.
'islands' becomes 'is' (i is an abbreviation for island).
'mused' placed around 'is' is 'MISUSED'.
'being' acts as a link.
(Other definitions for misused that I've seen before include "polluted, perhaps?" , "Applied wrongly" , "Falsely employed" , "wasted?" , "Treated badly" .)