Mischievous child crushed seed in hampers (7)
I believe the answer is:
impedes
'hampers' is the definition.
(I've seen this before)
'mischievous child crushed seed in' is the wordplay.
'mischievous child' becomes 'imp' (I've seen this before**).
'crushed' is an anagram indicator.
'in' is an insertion indicator.
'seed' is an anagram of 'edes'.
'imp' going inside 'edes' is 'IMPEDES'.
(Other definitions for impedes that I've seen before include "Hinders, obstructs" , "Obstructs, blocks" , "checks" , "Hampers" .)