Rings about train disaster in Canada (7)
I believe the answer is:
ontario
'in canada' is the definition.
(I know that Ontario is part of Canada)
'rings about train disaster' is the wordplay.
'rings' becomes 'oo' (multiple circles).
'about' indicates putting letters inside.
'disaster' indicates anagramming the letters.
'train' is an anagram of 'ntari'.
'oo' going around 'ntari' is 'ONTARIO'.
(Other definitions for ontario that I've seen before include "Province of central Canada" , "A North American lake" , "Canadian province and Great Lake" , "Smallest of the Great Lakes" , "Canadian Great lakes province" .)