Mischievous Eris expected rest (7)
I believe the answer is:
residue
'rest' is the definition.
(residue can mean the remains or rest of something)
'mischievous eris expected' is the wordplay.
'mischievous' indicates anagramming the letters.
'expected' becomes 'due' (similar in meaning).
'eris' with letters rearranged gives 'resi'.
'resi'+'due'='RESIDUE'
(Other definitions for residue that I've seen before include "grounds" , "What remains of something" , "Something remaining" , "Surplus" , "Leftovers" .)