Take issue with question to dispute the truth? (6)

I believe the answer is:

impugn

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'take issue with' is the definition.
(thesaurus)

I can't explain the rest of the clue.

(Other definitions for impugn that I've seen before include "Dispute honesty of (someone's motive)" , "Blacken the name of" , "Attack verbally" , "Call into question or attack by words" , "Call into question; criticise" .)

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

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