A French proviso a learner finds categorical (13)

I believe the answer is:

unconditional

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'categorical' is the definition.
(I know that categorical can be written as unconditional)

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for unconditional that I've seen before include "Categorical" , "Not qualified" , "without qualification" , "Absolute, unlimited" , "Under all circumstances" .)

I've seen this clue in The Times.

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