What a plaintive dog may do when I disturb it (5)

I believe the answer is:

whine

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'what a plaintive dog may do' is the definition.
The definition suggests a singular noun which matches the answer.

'when i disturb it' is the wordplay.
'when i' anagrams to 'WHINE'.
But, I am not clear how the anagram is indicated.

Can you help me to learn more?

(Other definitions for whine that I've seen before include "Nagging complaint" , "Moan" , "Complain peevishly" , "Complaining cry" , "Querulous complaining" .)

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

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