Unhealthy antagonism? (3-7)

I believe the answer is:

ill-feeling

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'unhealthy antagonism?' is the definition.
The definition suggests a singular noun which matches the answer.

'unhealthy antagonism?' is the wordplay.
'unhealthy' becomes 'i'll' (associated in meaning).
'antagonism?' becomes 'feeling' (antagonism is a kind of feeling).
'ill'+'feeling'='ILL-FEELING'

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

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