Run off at outset of disturbance (6)

I believe the answer is:

unrest

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'disturbance' is the definition.
(I've seen this before)

'run off at outset' is the wordplay.
'off' is an anagram indicator.
'at outset' becomes 'est' (I am not sure about this - if you are sure you should believe this answer much more).
'run' anagrammed gives 'unr'.
'unr'+'est'='UNREST'

'of' acts as a link.

Can you help me to learn more?

(Other definitions for unrest that I've seen before include "'Disturbance, agitation (6)'" , "Disorder" , "Uneasiness; turmoil" , "Turmoil, disquiet" , "Feeling of anxiety or turmoil" .)

I've seen this clue in The Globe and Mail.

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