One with theories on behaviour carrying less weight, one to avoid (7)

I believe the answer is:

skinner

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'one' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.

I cannot understand how the remainder of the clue works.

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(Other definitions for skinner that I've seen before include "Dennis, the Beast of Bolsover" , "expert in hiding?" .)

I've seen this clue in The Independent.

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