Suspects water vapour causes corrosion (9)

I believe the answer is:

mistrusts

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'suspects' is the definition.
(I know this)

'water vapour causes corrosion' is the wordplay.
'water vapour' becomes 'mist'.
'causes corrosion' becomes 'rusts' (I am not sure about this - if you are sure you should believe this answer much more).
'mist'+'rusts'='MISTRUSTS'

Can you help me to learn more?

(Another definition for mistrusts that I've seen is " Doubts".)

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

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