Examination involving segment of a ring road? (7)
I believe the answer is:
orbital
'a ring road?' is the definition.
(I've seen this before)
'examination involving segment' is the wordplay.
'examination' becomes 'oral' (oral is a kind of examination).
'involving' is an insertion indicator.
'segment' becomes 'bit' (I've seen this before).
'oral' enclosing 'bit' is 'ORBITAL'.
'of' is the link.
(Other definitions for orbital that I've seen before include "Circuitous" , "Of road, circling a town" , "The M 25, say" , "that's going around" , "Going round the world" .)