Nothing the matter? Look at horse! (5-3)

I believe the answer is:

goose-egg

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'nothing' is the definition.
(synonyms)

'matter? look at horse' is the wordplay.
'matter?' becomes 'goo' (I am not sure about this - if you are sure you should believe this answer much more).
'look at' becomes 'see' (I've seen this in another clue).
'horse' becomes 'gg' (geegee or GG is a childish term for a horse).
'goo'+'see'+'gg'='GOOSE-EGG'

'the' acts as a link.

Can you help me to learn more?

I've seen this clue in The Telegraph.

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