Snake attacks on Canada (8)
I believe the answer is:
anaconda
'snake' is the definition.
(anaconda is a kind of snake)
'attacks on canada' is the wordplay.
'attacks' indicates anagramming the letters (I've seen 'attacked' mean this).
'on'+'canada'='oncanada'
'oncanada' with letters rearranged gives 'ANACONDA'.
(Other definitions for anaconda that I've seen before include "Water-boa" , "A slippery customer" , "One can get crush on" , "Large South American snake" , "Water boa" .)