Proust oddly missing dreary routine (3)
I believe the answer is:
rut
'dreary routine' is the definition.
(I've seen this before)
'proust oddly missing' is the wordplay.
'oddly missing' means one should take alternating letters (letters in odd-numbered positions removed).
The alternating letters of 'proust' are 'RUT'.
(Other definitions for rut that I've seen before include "Mating period for deer" , "It's hard to get out of" , "Settled routine" , "Road depression, difficult to get out of" , "Long deep track" .)