Extremely dubious clue he prepared for list (8)
I believe the answer is:
schedule
'for list' is the definition.
(schedule is a kind of list)
'extremely dubious clue he prepared' is the wordplay.
'extremely' says to hollow out the word (remove centre letters) (only the extremes of the word are used).
'prepared' indicates an anagram.
'dubious' with its middle taken out is 'ds'.
'ds'+'clue'+'he'='dscluehe'
'dscluehe' with letters rearranged gives 'SCHEDULE'.
(Other definitions for schedule that I've seen before include "Timetable of planned events or work" , "Programme or timetable of planned events" , "Timetable for activities" , "Rota" , "Timetable; plan of action" .)