Insect was initially found in each fiddle (6)
I believe the answer is:
earwig
'insect' is the definition.
(earwig is a kind of insect)
'was initially found in each fiddle' is the wordplay.
'initially' suggests taking the first letters.
'found in' indicates putting letters inside.
'each' becomes 'ea'.
'fiddle' becomes 'rig' (I've seen this before**).
The first letter of 'was' is 'w'.
'ea'+'rig'='earig'
'w' put into 'earig' is 'EARWIG'.
(Other definitions for earwig that I've seen before include "Tap" , "creepy-crawly" , "Aural appendage and head covering for an insect" , "Small insect with aural toupee?" , "court" .)