Proust ran off in a daze (6)
I believe the answer is:
stupor
'in a daze' is the definition.
(I've seen this before)
'proust ran' is the wordplay.
'ran' is an anagram indicator (letters have run around).
'proust' with letters rearranged gives 'STUPOR'.
'off' acts as a link.
(Other definitions for stupor that I've seen before include "Stupefaction, daze" , "State of lethargy" , "Daze or torpor" , "Shocked or drunken state" , "Proust found in dazed condition" .)