Many hours in stupor, reportedly (4)
I believe the answer is:
days
'many hours' is the definition.
(I've seen this in another clue)
'stupor reportedly' is the wordplay.
'stupor' becomes 'daze' (synonyms).
'reportedly' indicates a 'sounds like' (homophone) clue.
'daze' sounds like 'DAYS'.
'in' is the link.
(Other definitions for days that I've seen before include "Times" , "Periods (of week)" , "See 25" , "Sevenths of a week" , "Periods of 24 hours" .)