Maltreated pet rescued is in a state (10)
I believe the answer is:
persecuted
'maltreated' is the definition.
Both the answer and definition are adjectives. Maybe they are linked in a way I don't understand?
'pet rescued is in a state' is the wordplay.
'is in a state' is an anagram indicator (the letters in confusion or chaos).
'pet'+'rescued'='petrescued'
'petrescued' anagrammed gives 'PERSECUTED'.
Can you help me to learn more?
(Other definitions for persecuted that I've seen before include "Ill-treated" , "abused" , "Persistently harassed" .)