Virtuous maybe but losing out to harmful influence (5)

I believe the answer is:

virus

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'influence' is the definition.
(I have seen 'Corrupting influence' mean 'virus' so perhaps 'influence' could also mean 'virus')

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for virus that I've seen before include "Cause of infection (in people and computers)" , "Malicious code" , "Harmful computer code" , "Hidden destructive code in computer program - makes you sick" , "Ultramicroscopic infectious agent" .)

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

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