He would solve clues about plan (8)
I believe the answer is:
schedule
'plan' is the definition.
(I know that plan is a is a more specific form of the action of schedule)
'he would solve clues about' is the wordplay.
'would' becomes 'd' (I've seen this in other clues).
'solve' indicates anagramming the letters (I've seen 'solving' mean this (anagrams are puzzles)).
'about' is an insertion indicator.
'clues' with letters rearranged gives 'scule'.
'he'+'d'='hed'
'hed' put inside 'scule' is 'SCHEDULE'.
(Other definitions for schedule that I've seen before include "Agenda" , "Timetable of planned events or work" , "List - inventory" , "You don't see loafers on this" , "Plan of times and events" .)