Sure I'd misplaced almost all the rest (8)
I believe the answer is:
residual
'the rest' is the definition.
(thesaurus)
'sure i'd misplaced almost all' is the wordplay.
'misplaced' indicates an anagram.
'almost' means to remove the last letter (most of the word but not all of it).
'all' with its final letter removed is 'al'.
'sure'+'id'='sureid'
'sureid' is an anagram of 'residu'.
'residu'+'al'='RESIDUAL'
(Other definitions for residual that I've seen before include "Left over as a remainder" , "Remaining at the end" , "'Remaining, left over (8)'" , "Pertaining to what is left over" , "unused" .)