Retired with time sure to be wasted (8)
I believe the answer is:
emeritus
'retired' is the definition.
(I've seen this before)
'with time sure to be wasted' is the wordplay.
'with' means one lot of letters go next to another.
'to be wasted' indicates anagramming the letters.
'time' next to 'sure' is 'timesure'.
'timesure' with letters rearranged gives 'EMERITUS'.
(Other definitions for emeritus that I've seen before include "Keeping hon. title in retirement" , "No longer having old chair" , "Use merit to describe retained title" , "Retired but retaining a courtesy title" , "Retired and retaining title, say professor" .)