For inner mechanisms, a full treatment (3,5)

I believe the answer is:

the works

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'treatment' is the definition.
(I have seen 'Comprehensive treatment' mean 'the works' so perhaps 'treatment' could also mean 'the works')

I cannot understand how the remainder of the clue works.

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(Other definitions for the works that I've seen before include "plant?" , "factory?" , "(Give it) everything" , "Comprehensive treatment" .)

I've seen this clue in the Evening Standard.

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