Proust reinterpreted produces mental dullness (6)
I believe the answer is:
stupor
'mental dullness' is the definition.
(stupor means a dull state of mind)
'proust reinterpreted' is the wordplay.
'reinterpreted' indicates anagramming the letters.
'proust' with letters rearranged gives 'STUPOR'.
'produces' acts as a link.
(Other definitions for stupor that I've seen before include "that'll send you to sleep" , "Suspension of sensibility" , "State of lethargy" , "Marginal consciousness" , "State of being stunned" .)