Asserted medical disaster (7)
I believe the answer is:
claimed
'asserted' is the definition.
(claiming is a kind of asserting)
'medical disaster' is the wordplay.
'disaster' indicates an anagram.
'medical' with letters rearranged gives 'CLAIMED'.
(Other definitions for claimed that I've seen before include "Alleged" , "Declared" , "Asserted one's right to" , "Asserted, contended" , "Asserted right to or interest in" .)