One finds things funny? That's horrible in genuine upset! (7)

I believe the answer is:

laugher

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'one finds things funny?' is the definition.
I can't judge whether this definition defines the answer.

'horrible in genuine upset' is the wordplay.
'horrible' becomes 'ugh' (expression of disgust).
'in' is an insertion indicator.
'genuine' becomes 'real' (similar in meaning).
'upset' shows that the letters should be reversed in order.
'real' backwards is 'laer'.
'ugh' placed within 'laer' is 'LAUGHER'.

'that's' acts as a link.

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I've seen this clue in The Times.

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