'T isn't corrupt (5)

I believe the answer is:

taint

'corrupt' is the definition.
(I've seen this before)

''t isn't' is the wordplay.
'isn't' becomes 'aint' (I've seen this before).
't'+'aint'='TAINT'

(Other definitions for taint that I've seen before include "Contaminate, pollute" , "Blemish" , "contaminant" , "Adulterate" , "Defect - contamination" .)

I've seen this clue in The Times.

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