Mischievously suggest bagging his nuts (8)
I believe the answer is:
impishly
'mischievously' is the definition.
(I've seen this before)
'suggest bagging his nuts' is the wordplay.
'suggest' becomes 'imply' (implying is a kind of suggesting**).
'bagging' indicates putting letters inside (I've seen this in other clues).
'nuts' indicates an anagram (nuts can mean crazy).
'his' is an anagram of 'ish'.
'imply' going around 'ish' is 'IMPISHLY'.
(Other definitions for impishly that I've seen before include "In a mischievous manner" , "In a mischievous way" , "In mischievous fashion" , "like a naughty child" , "Mischievously" .)