Initially canines stay calm around upheaval (9)
I believe the answer is:
cataclysm
'upheaval' is the definition.
(I have seen 'Disastrous upheaval' mean 'cataclysm' so perhaps 'upheaval' could also mean 'cataclysm')
'initially canines stay calm around' is the wordplay.
'initially' says to take the initial letters.
'around' indicates anagramming the letters.
The first letter of 'canines' is 'c'.
'stay'+'calm'='staycalm'
'staycalm' is an anagram of 'ataclysm'.
'c'+'ataclysm'='CATACLYSM'
(Other definitions for cataclysm that I've seen before include "Sudden violent change in the earth's surface" , "A clam cyst could be a disaster" , "Violent event" , "Disastrous upheaval or flood" , "Event resulting in great loss and misfortune" .)