Deduce there’s justification (6)

I believe the answer is:

reason

This clue is a double definition.

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

'justification' is the second definition.
(thesaurus)

'there's' is the link.

(Other definitions for reason that I've seen before include "The right exercise of the mind" , "Justification or motive" , "Explanation or justification" , "Cause for sanity" , "use of wit" .)

I've seen this clue in the Evening Standard.

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