Dying? Agree to be treated! (5)
I believe the answer is:
eager
'dying?' is the definition.
(thesaurus)
'agree to be treated' is the wordplay.
'to be treated' indicates anagramming the letters.
'agree' is an anagram of 'EAGER'.
(Other definitions for eager that I've seen before include "willing" , "Thirsty" , "Low platform" , "Anxious" , "Longing to see" .)