He's clued about plan (8)
I believe the answer is:
schedule
'plan' is the definition.
(I know this)
'he's clued about' is the wordplay.
'about' indicates anagramming the letters.
'hes'+'clued'='hesclued'
'hesclued' anagrammed gives 'SCHEDULE'.
(Other definitions for schedule that I've seen before include "Programme or timetable of planned events" , "Timetable for activities" , "Agenda" , "List of intended events and times" , "List of times when things should happen" .)