Questions the validity of licence for popguns (7)

I believe the answer is:

oppugns

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

'validity of licence for popguns' is the wordplay.
'popguns' can be anagrammed to 'OPPUGNS'.
However, I'm unsure how this is indicated.

'the' acts as a link.

Can you help me to learn more?

I've seen this clue in The Independent.

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