Dog reportedly moves unsteadily? It’s the tummy trouble (12)

I believe the answer is:

collywobbles

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'it's the tummy trouble' is the definition.
I can't tell whether this definition defines the answer.

'dog reportedly moves unsteadily?' is the wordplay.
'dog' becomes 'collie' (collie is a kind of dog).
'reportedly' shows a homophone (sound like).
'moves unsteadily?' becomes 'wobbles' ('wobble' can be a synonym of 'move unsteadily').
'collie' is a homophone of 'colly'.
'colly'+'wobbles'='COLLYWOBBLES'

Can you help me to learn more?

(Other definitions for collywobbles that I've seen before include "Owls by Belloc (anag) -- severe gastroenteritis" , "Abdominal pain (causing feelings of apprehension?)" , "Upset stomach" , "Intense anxiety" , "Nervous apprehension" .)

I've seen this clue in The Times.

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