Part involved in examination of circuit (7)
I believe the answer is:
orbital
'part involved in examination of circuit' is the definition.
I can't tell whether this definition defines the answer.
'part involved in examination' is the wordplay.
'part' becomes 'bit' (both mean a piece of something).
'involved in' is an insertion indicator.
'examination' becomes 'oral' (oral is a kind of examination).
'bit' going into 'oral' is 'ORBITAL'.
Can you help me to learn more?
(Other definitions for orbital that I've seen before include "that's going around" , "Like a sort of road" , "kind of motorway" , "Relating to planet's motion" , "(Of a road) going round a town" .)