An issue for the HSE? One is better off without it! (8)

I believe the answer is:

sickness

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'it' is the definition.
The definition suggests a singular noun which matches the answer.

I cannot understand how the remainder of the clue works.

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(Other definitions for sickness that I've seen before include "State of being ill" , "It's not looking good" , "Ailment" , "Illness, disease" , "State of ill-health, malady" .)

I've seen this clue in the Irish Times (Crosaire) and the Irish Times.

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