Thinner version of Proust in which nothing is forgotten (5)

I believe the answer is:

turps

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

I don't understand how the remainder of the clue works.

(Other definitions for turps that I've seen before include "Brush-cleaning spirit" , "Paint thinner or solvent (abbr)" , "Brush cleaning fluid" , "Paint/varnish ingredient" , "Oil used in paints" .)

I've seen this clue in The Independent.

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