Looked mischievous, being found in pit (8)
I believe the answer is:
searched
'looked' is the definition.
('search' can be a synonym of 'look')
'mischievous being found in pit' is the wordplay.
'mischievous' becomes 'arch' (I've seen this before).
'being found in' is an insertion indicator.
'pit' becomes 'seed' ('pit' is a US term for the stone of a fruit).
'arch' placed into 'seed' is 'SEARCHED'.
(Other definitions for searched that I've seen before include "Sought, scoured" , "Spent time trying to find" , "Sought to find" , "Tried to locate" , "Sought, looked through" .)